Get the biggest chronological drop, min and max from an array with O(n)

up vote
8
down vote

favorite

I have written a javascript function for analyzing the biggest drop in an array. But one little issue is still there. As the max value, I always get max value from my hole array and not from my drop.

Example:
Array: [100,90,80,120]

The biggest drop would be between 100 and 80. So max must be 100, and min 80. My function always returns the highest value from the whole array. in my case 120

function checkData(data) {

  let max = 0

  let min = 0

  let drop = 0



  for (let i = 0; i < data.length; i++) {

      if (max < data[i]) {

          max = data[i] //?

      } else {

          let tempDrop = max - data[i]

          drop = Math.max(tempDrop, drop)

          min = max - drop

      }

  }

  return [max, min, drop]

}

I want to get the chronological correct biggest delta from left to right
Demo Image

edited Nov 26 at 13:20

asked Nov 26 at 12:36

Pommesloch

19510

1

When you say drop, do you mean difference?
– cmprogram
Nov 26 at 12:40

@cmprogram, I mean the biggest delta between max an min.
– Pommesloch
Nov 26 at 12:41

1

is this array sorted? what do you mean by saying drop?
– yossico
Nov 26 at 12:41

return [max, min, drop] What are max, min and drop?
– Wais Kamal
Nov 26 at 12:42

what would be the drop output to [100,110,120,70,60,50,90,300,200]?
– yossico
Nov 26 at 12:42

|
show 11 more comments

up vote
8
down vote

favorite

I have written a javascript function for analyzing the biggest drop in an array. But one little issue is still there. As the max value, I always get max value from my hole array and not from my drop.

Example:
Array: [100,90,80,120]

The biggest drop would be between 100 and 80. So max must be 100, and min 80. My function always returns the highest value from the whole array. in my case 120

function checkData(data) {

  let max = 0

  let min = 0

  let drop = 0



  for (let i = 0; i < data.length; i++) {

      if (max < data[i]) {

          max = data[i] //?

      } else {

          let tempDrop = max - data[i]

          drop = Math.max(tempDrop, drop)

          min = max - drop

      }

  }

  return [max, min, drop]

}

I want to get the chronological correct biggest delta from left to right
Demo Image

edited Nov 26 at 13:20

asked Nov 26 at 12:36

Pommesloch

19510

1

When you say drop, do you mean difference?
– cmprogram
Nov 26 at 12:40

@cmprogram, I mean the biggest delta between max an min.
– Pommesloch
Nov 26 at 12:41

1

is this array sorted? what do you mean by saying drop?
– yossico
Nov 26 at 12:41

return [max, min, drop] What are max, min and drop?
– Wais Kamal
Nov 26 at 12:42

what would be the drop output to [100,110,120,70,60,50,90,300,200]?
– yossico
Nov 26 at 12:42

|
show 11 more comments

up vote
8
down vote

favorite

I have written a javascript function for analyzing the biggest drop in an array. But one little issue is still there. As the max value, I always get max value from my hole array and not from my drop.

Example:
Array: [100,90,80,120]

The biggest drop would be between 100 and 80. So max must be 100, and min 80. My function always returns the highest value from the whole array. in my case 120

function checkData(data) {

  let max = 0

  let min = 0

  let drop = 0



  for (let i = 0; i < data.length; i++) {

      if (max < data[i]) {

          max = data[i] //?

      } else {

          let tempDrop = max - data[i]

          drop = Math.max(tempDrop, drop)

          min = max - drop

      }

  }

  return [max, min, drop]

}

I want to get the chronological correct biggest delta from left to right
Demo Image

edited Nov 26 at 13:20

asked Nov 26 at 12:36

Pommesloch

19510

I have written a javascript function for analyzing the biggest drop in an array. But one little issue is still there. As the max value, I always get max value from my hole array and not from my drop.

Example:
Array: [100,90,80,120]

The biggest drop would be between 100 and 80. So max must be 100, and min 80. My function always returns the highest value from the whole array. in my case 120

function checkData(data) {

  let max = 0

  let min = 0

  let drop = 0



  for (let i = 0; i < data.length; i++) {

      if (max < data[i]) {

          max = data[i] //?

      } else {

          let tempDrop = max - data[i]

          drop = Math.max(tempDrop, drop)

          min = max - drop

      }

  }

  return [max, min, drop]

}

I want to get the chronological correct biggest delta from left to right
Demo Image

javascript arrays algorithm calculation

edited Nov 26 at 13:20

asked Nov 26 at 12:36

Pommesloch

19510

edited Nov 26 at 13:20

asked Nov 26 at 12:36

Pommesloch

19510

edited Nov 26 at 13:20

asked Nov 26 at 12:36

Pommesloch

19510

asked Nov 26 at 12:36

Pommesloch

19510

asked Nov 26 at 12:36

Pommesloch

19510

1

When you say drop, do you mean difference?
– cmprogram
Nov 26 at 12:40

@cmprogram, I mean the biggest delta between max an min.
– Pommesloch
Nov 26 at 12:41

1

is this array sorted? what do you mean by saying drop?
– yossico
Nov 26 at 12:41

return [max, min, drop] What are max, min and drop?
– Wais Kamal
Nov 26 at 12:42

what would be the drop output to [100,110,120,70,60,50,90,300,200]?
– yossico
Nov 26 at 12:42

|
show 11 more comments

1

When you say drop, do you mean difference?
– cmprogram
Nov 26 at 12:40

@cmprogram, I mean the biggest delta between max an min.
– Pommesloch
Nov 26 at 12:41

1

is this array sorted? what do you mean by saying drop?
– yossico
Nov 26 at 12:41

return [max, min, drop] What are max, min and drop?
– Wais Kamal
Nov 26 at 12:42

what would be the drop output to [100,110,120,70,60,50,90,300,200]?
– yossico
Nov 26 at 12:42

When you say drop, do you mean difference?
– cmprogram
Nov 26 at 12:40

@cmprogram, I mean the biggest delta between max an min.
– Pommesloch
Nov 26 at 12:41

is this array sorted? what do you mean by saying drop?
– yossico
Nov 26 at 12:41

return [max, min, drop] What are max, min and drop?
– Wais Kamal
Nov 26 at 12:42

what would be the drop output to [100,110,120,70,60,50,90,300,200]?
– yossico
Nov 26 at 12:42

|
show 11 more comments

6 Answers
6

active

oldest

votes

up vote
6
down vote

accepted

Your loop should keep track of the current drop and compare it to the previous largest drop. You can do this by tracking indexes:

function checkData(data) {

  let bestDropStart = 0

  let bestDropEnd = 0

  let bestDrop = 0

  let currentDropStart = 0

  let currentDropEnd = 0

  let currentDrop = 0

  for (let i = 1; i < data.length; i++) {

    if (data[i] < data[i - 1]) {

      // we are dropping

      currentDropEnd = i

      currentDrop = data[currentDropStart] - data[i]

    } else {

      // the current drop ended; check if it's better

      if (currentDrop > bestDrop) {

        bestDrop = currentDrop

        bestDropStart = currentDropStart

        bestDropEnd = currentDropEnd

      }

      // start a new drop

      currentDropStart = currentDropEnd = i

      currentDrop = 0

    }

  }

  // check for a best drop at end of data

  if (currentDrop > bestDrop) {

    bestDrop = currentDrop

    bestDropStart = currentDropStart

    bestDropEnd = currentDropEnd

  }

  // return the best drop data

  return [data[bestDropStart], data[bestDropEnd], bestDrop]

}



console.log(checkData([100, 90, 80, 120]))

console.log(checkData([100, 90, 80, 120, 30]))

console.log(checkData([70, 100, 90, 80]))

console.log(checkData([100, 90, 80, 120, 30, 50]))

You can also do it by just keeping the start and end values for the current and best drops, but my preference would be to explicitly track the indexes. It just seems clearer (easier to debug and maintain) to me that way.

edited Nov 26 at 15:39

answered Nov 26 at 13:56

Ted Hopp

198k41311421

add a comment |

up vote
2
down vote

It sounds like you'd like the returned max and min to be the same ones used in calculating the largest drop rather than the overall max and min. In that case just add an additional variable to store those when drop is updated. Replace

drop = Math.max(tempDrop, drop)

with an if statement (pseudocode):

if current_drop is greater than stored_drop:

  stored_drop = current_drop

  stored_max_min = current max and min

then return the additional stored max and min.

answered Nov 26 at 13:39

גלעד ברקן

12k21439

add a comment |

up vote
2
down vote

You need to iterate the array once (O(n)) and keep a running count of min and max values and:

Reset it every time the value increases w.r.t. previous value

But note them down if the difference is greater than previously noted values

function checkData(array) {

  var currentmax = array[0];

  var currentmin = array[0];

  var overallmax = array[0];

  var overallmin = array[0];

  var i;

  for (i = 1; i < array.length; i++) {

    if (array[i] <= array[i - 1]) {

      // value is same or decreased

      currentmin = array[i];

    } else {

      // check if previous iteration was the largest

      if (currentmax - currentmin > overallmax - overallmin) {

        overallmax = currentmax;

        overallmin = currentmin;

      }

      // restart

      currentmax = array[i];

      currentmin = array[i];

    }

  }

  // check if last iteration was the largest

  if (currentmax - currentmin > overallmax - overallmin) {

    overallmax = currentmax;

    overallmin = currentmin;

  }



  return [overallmax, overallmin, overallmax - overallmin];

}

console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100, 90]));

console.log(checkData([10, 100, 50, 50, 10, 100, 50, 50, 1]));

edited Nov 26 at 15:16

answered Nov 26 at 13:36

Salman A

174k66334421

This fails for [100, 90, 80, 120, 200, 100 ,90]. The return must be max = 200, min = 90 and drop = 110
– Pommesloch
Nov 26 at 13:50

1

the logic is sound (I think) and i just need to update the max min everytime the values change. See revised answer.
– Salman A
Nov 26 at 13:55

add a comment |

up vote
0
down vote

You need to keep track of two things:

The maximum value you have up to an element i.

The minimum value you have from an element i to the end of the list.

Then you just need to find the drop for each index and select which one is biggest.

Here is the code:

function maxDrop (data) {

  if (!data || data.length === 0) {

    return;

  }

  const max = ;

  const min = ;

  for (let i = 0; i < data.length; i++) {

    const left = data.slice(0, i);

    const right = data.slice(i, data.length);

    max.push(Math.max.apply(null, left));

    min.push(Math.min.apply(null, right));

  }

  let maxDrop = max[0] - min[0];

  let maxValue = max[0];

  let minValue = min[0];

  for (let j = 0; j < data.length; j++) {

    const drop = max[j] - min[j];

    if (maxDrop < drop) {

      maxDrop = drop;

      maxValue = max[j];

      minValue = min[j];

    }

  }

  return [maxValue, minValue, maxDrop];

}



console.log(maxDrop([100,90,80,120]))

console.log(maxDrop([100,110,120,300,200,70,60,50,90,400]))

console.log(maxDrop([100,90,80,120,30]))

edited Nov 26 at 13:55

answered Nov 26 at 13:34

kakamg0

82649

This fails for [100, 90, 80, 120, 30]. The output is [100, 80, 20] but it should be [120, 30, 90].
– Ted Hopp
Nov 26 at 13:37

@TedHopp Fixed it, I was excluding the last element when searching for the minimum value. Thanks!
– kakamg0
Nov 26 at 13:56

add a comment |

up vote
0
down vote

To add one more to the mix..
A possible approach is to create all the drop - ranges first, than get the one with the largest drop

A version with reduce:

function checkData(data) {

let dropInd = 1,

  	mx = data.reduce((arr,val, ind) => {

 if(ind && val > data[ind-1])dropInd++;  	      

 arr[dropInd] = arr[dropInd] || {max:val};

 arr[dropInd].min = val;

 arr[dropInd].drop = arr[dropInd].max - val;

 return arr;

}, ) //after reduce, islands are created based on 'dropInd'  

  .sort((v1,v2)=>v2.drop - v1.drop) //sort by drop descending

  [0]; //the first value now contains the maximum drop  



  return [mx.max,mx.min,mx.drop];

}







console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100 ,90]));

console.log(checkData([200,100, 90, 80, 120,  100 ,90]));

console.log(checkData([200,120,190, 90, 80, 120,  100 ,90]));

edited Nov 26 at 16:17

answered Nov 26 at 14:12

Me.Name

10.1k22039

add a comment |

up vote
-1
down vote

This works exactly as intended (as per your expected output), as shown in the following code snippet.

The issue must be in how you are sending your data as an array.

alert(checkData([100, 90, 80, 120]));



function checkData(data) {

  let max = 0

  let min = 0

  let drop = 0



  for (let i = 0; i < data.length; i++) {

    if (max < data[i]) {

      max = data[i] //?

    } else {

      let tempDrop = max - data[i]

      drop = Math.max(tempDrop)

      min = max - drop

    }

  }

  return [max, min, drop]

}

// Output : 120, 80, 20

However, if what you are looking for is a Max, a Min, and then the biggest difference, i.e. between the the max and min, which in your given example would be 40, then you can simply do this.

alert(checkData([100, 90, 80, 120]));



function checkData(data) {



  let max = data.reduce(function(a, b) {

    return Math.max(a, b);

  });

  let min = data.reduce(function(a, b) {

    return Math.min(a, b);

  });



  let drop = max-min;



  return [max, min, drop];

  

}

// Output : 120, 80, 40

I only mention this as I don't know why you've said you expect the biggest difference to be 20, given 100 and 80, when you have 120 and 80 in the same array, meaning the biggest difference is 40.

edited Nov 26 at 13:01

answered Nov 26 at 12:50

cmprogram

1,063519

Thanks, but the correct return must be max = 100, min = 80 and drop = 20. Look at the graphic that I added to my post
– Pommesloch
Nov 26 at 13:11

But 100 isn't the max... If you don't want the 120 to be included, just don't include it in the array...
– cmprogram
Nov 26 at 13:13

This data comes from a shares API. That is why I need this chronological from left to right delta. The shares course is crashed here from 100 to 80. This is a -20% drop. In my attempt, I miss the chronological aspect
– Pommesloch
Nov 26 at 13:18

1

OP wants the max and min associated with the largest drop, where a drop is a sequence of descending data values. The largest drop is from 100 to 80 (indexes 0 through 2).
– Ted Hopp
Nov 26 at 13:34

add a comment |

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6 Answers
6

active

oldest

votes

6 Answers
6

active

oldest

votes

up vote
6
down vote

accepted

Your loop should keep track of the current drop and compare it to the previous largest drop. You can do this by tracking indexes:

function checkData(data) {

  let bestDropStart = 0

  let bestDropEnd = 0

  let bestDrop = 0

  let currentDropStart = 0

  let currentDropEnd = 0

  let currentDrop = 0

  for (let i = 1; i < data.length; i++) {

    if (data[i] < data[i - 1]) {

      // we are dropping

      currentDropEnd = i

      currentDrop = data[currentDropStart] - data[i]

    } else {

      // the current drop ended; check if it's better

      if (currentDrop > bestDrop) {

        bestDrop = currentDrop

        bestDropStart = currentDropStart

        bestDropEnd = currentDropEnd

      }

      // start a new drop

      currentDropStart = currentDropEnd = i

      currentDrop = 0

    }

  }

  // check for a best drop at end of data

  if (currentDrop > bestDrop) {

    bestDrop = currentDrop

    bestDropStart = currentDropStart

    bestDropEnd = currentDropEnd

  }

  // return the best drop data

  return [data[bestDropStart], data[bestDropEnd], bestDrop]

}



console.log(checkData([100, 90, 80, 120]))

console.log(checkData([100, 90, 80, 120, 30]))

console.log(checkData([70, 100, 90, 80]))

console.log(checkData([100, 90, 80, 120, 30, 50]))

edited Nov 26 at 15:39

answered Nov 26 at 13:56

Ted Hopp

198k41311421

add a comment |

up vote
6
down vote

accepted

Your loop should keep track of the current drop and compare it to the previous largest drop. You can do this by tracking indexes:

function checkData(data) {

  let bestDropStart = 0

  let bestDropEnd = 0

  let bestDrop = 0

  let currentDropStart = 0

  let currentDropEnd = 0

  let currentDrop = 0

  for (let i = 1; i < data.length; i++) {

    if (data[i] < data[i - 1]) {

      // we are dropping

      currentDropEnd = i

      currentDrop = data[currentDropStart] - data[i]

    } else {

      // the current drop ended; check if it's better

      if (currentDrop > bestDrop) {

        bestDrop = currentDrop

        bestDropStart = currentDropStart

        bestDropEnd = currentDropEnd

      }

      // start a new drop

      currentDropStart = currentDropEnd = i

      currentDrop = 0

    }

  }

  // check for a best drop at end of data

  if (currentDrop > bestDrop) {

    bestDrop = currentDrop

    bestDropStart = currentDropStart

    bestDropEnd = currentDropEnd

  }

  // return the best drop data

  return [data[bestDropStart], data[bestDropEnd], bestDrop]

}



console.log(checkData([100, 90, 80, 120]))

console.log(checkData([100, 90, 80, 120, 30]))

console.log(checkData([70, 100, 90, 80]))

console.log(checkData([100, 90, 80, 120, 30, 50]))

edited Nov 26 at 15:39

answered Nov 26 at 13:56

Ted Hopp

198k41311421

add a comment |

up vote
6
down vote

accepted

Your loop should keep track of the current drop and compare it to the previous largest drop. You can do this by tracking indexes:

function checkData(data) {

  let bestDropStart = 0

  let bestDropEnd = 0

  let bestDrop = 0

  let currentDropStart = 0

  let currentDropEnd = 0

  let currentDrop = 0

  for (let i = 1; i < data.length; i++) {

    if (data[i] < data[i - 1]) {

      // we are dropping

      currentDropEnd = i

      currentDrop = data[currentDropStart] - data[i]

    } else {

      // the current drop ended; check if it's better

      if (currentDrop > bestDrop) {

        bestDrop = currentDrop

        bestDropStart = currentDropStart

        bestDropEnd = currentDropEnd

      }

      // start a new drop

      currentDropStart = currentDropEnd = i

      currentDrop = 0

    }

  }

  // check for a best drop at end of data

  if (currentDrop > bestDrop) {

    bestDrop = currentDrop

    bestDropStart = currentDropStart

    bestDropEnd = currentDropEnd

  }

  // return the best drop data

  return [data[bestDropStart], data[bestDropEnd], bestDrop]

}



console.log(checkData([100, 90, 80, 120]))

console.log(checkData([100, 90, 80, 120, 30]))

console.log(checkData([70, 100, 90, 80]))

console.log(checkData([100, 90, 80, 120, 30, 50]))

edited Nov 26 at 15:39

answered Nov 26 at 13:56

Ted Hopp

198k41311421

Your loop should keep track of the current drop and compare it to the previous largest drop. You can do this by tracking indexes:

function checkData(data) {

  let bestDropStart = 0

  let bestDropEnd = 0

  let bestDrop = 0

  let currentDropStart = 0

  let currentDropEnd = 0

  let currentDrop = 0

  for (let i = 1; i < data.length; i++) {

    if (data[i] < data[i - 1]) {

      // we are dropping

      currentDropEnd = i

      currentDrop = data[currentDropStart] - data[i]

    } else {

      // the current drop ended; check if it's better

      if (currentDrop > bestDrop) {

        bestDrop = currentDrop

        bestDropStart = currentDropStart

        bestDropEnd = currentDropEnd

      }

      // start a new drop

      currentDropStart = currentDropEnd = i

      currentDrop = 0

    }

  }

  // check for a best drop at end of data

  if (currentDrop > bestDrop) {

    bestDrop = currentDrop

    bestDropStart = currentDropStart

    bestDropEnd = currentDropEnd

  }

  // return the best drop data

  return [data[bestDropStart], data[bestDropEnd], bestDrop]

}



console.log(checkData([100, 90, 80, 120]))

console.log(checkData([100, 90, 80, 120, 30]))

console.log(checkData([70, 100, 90, 80]))

console.log(checkData([100, 90, 80, 120, 30, 50]))

function checkData(data) {

  let bestDropStart = 0

  let bestDropEnd = 0

  let bestDrop = 0

  let currentDropStart = 0

  let currentDropEnd = 0

  let currentDrop = 0

  for (let i = 1; i < data.length; i++) {

    if (data[i] < data[i - 1]) {

      // we are dropping

      currentDropEnd = i

      currentDrop = data[currentDropStart] - data[i]

    } else {

      // the current drop ended; check if it's better

      if (currentDrop > bestDrop) {

        bestDrop = currentDrop

        bestDropStart = currentDropStart

        bestDropEnd = currentDropEnd

      }

      // start a new drop

      currentDropStart = currentDropEnd = i

      currentDrop = 0

    }

  }

  // check for a best drop at end of data

  if (currentDrop > bestDrop) {

    bestDrop = currentDrop

    bestDropStart = currentDropStart

    bestDropEnd = currentDropEnd

  }

  // return the best drop data

  return [data[bestDropStart], data[bestDropEnd], bestDrop]

}



console.log(checkData([100, 90, 80, 120]))

console.log(checkData([100, 90, 80, 120, 30]))

console.log(checkData([70, 100, 90, 80]))

console.log(checkData([100, 90, 80, 120, 30, 50]))

function checkData(data) {

  let bestDropStart = 0

  let bestDropEnd = 0

  let bestDrop = 0

  let currentDropStart = 0

  let currentDropEnd = 0

  let currentDrop = 0

  for (let i = 1; i < data.length; i++) {

    if (data[i] < data[i - 1]) {

      // we are dropping

      currentDropEnd = i

      currentDrop = data[currentDropStart] - data[i]

    } else {

      // the current drop ended; check if it's better

      if (currentDrop > bestDrop) {

        bestDrop = currentDrop

        bestDropStart = currentDropStart

        bestDropEnd = currentDropEnd

      }

      // start a new drop

      currentDropStart = currentDropEnd = i

      currentDrop = 0

    }

  }

  // check for a best drop at end of data

  if (currentDrop > bestDrop) {

    bestDrop = currentDrop

    bestDropStart = currentDropStart

    bestDropEnd = currentDropEnd

  }

  // return the best drop data

  return [data[bestDropStart], data[bestDropEnd], bestDrop]

}



console.log(checkData([100, 90, 80, 120]))

console.log(checkData([100, 90, 80, 120, 30]))

console.log(checkData([70, 100, 90, 80]))

console.log(checkData([100, 90, 80, 120, 30, 50]))

edited Nov 26 at 15:39

answered Nov 26 at 13:56

Ted Hopp

198k41311421

edited Nov 26 at 15:39

answered Nov 26 at 13:56

Ted Hopp

198k41311421

answered Nov 26 at 13:56

Ted Hopp

198k41311421

answered Nov 26 at 13:56

Ted Hopp

198k41311421

add a comment |

up vote
2
down vote

drop = Math.max(tempDrop, drop)

with an if statement (pseudocode):

if current_drop is greater than stored_drop:

  stored_drop = current_drop

  stored_max_min = current max and min

then return the additional stored max and min.

answered Nov 26 at 13:39

גלעד ברקן

12k21439

add a comment |

up vote
2
down vote

drop = Math.max(tempDrop, drop)

with an if statement (pseudocode):

if current_drop is greater than stored_drop:

  stored_drop = current_drop

  stored_max_min = current max and min

then return the additional stored max and min.

answered Nov 26 at 13:39

גלעד ברקן

12k21439

add a comment |

up vote
2
down vote

drop = Math.max(tempDrop, drop)

with an if statement (pseudocode):

if current_drop is greater than stored_drop:

  stored_drop = current_drop

  stored_max_min = current max and min

then return the additional stored max and min.

answered Nov 26 at 13:39

גלעד ברקן

12k21439

drop = Math.max(tempDrop, drop)

with an if statement (pseudocode):

if current_drop is greater than stored_drop:

  stored_drop = current_drop

  stored_max_min = current max and min

then return the additional stored max and min.

answered Nov 26 at 13:39

גלעד ברקן

12k21439

answered Nov 26 at 13:39

גלעד ברקן

12k21439

answered Nov 26 at 13:39

גלעד ברקן

12k21439

answered Nov 26 at 13:39

גלעד ברקן

12k21439

add a comment |

up vote
2
down vote

You need to iterate the array once (O(n)) and keep a running count of min and max values and:

Reset it every time the value increases w.r.t. previous value

But note them down if the difference is greater than previously noted values

function checkData(array) {

  var currentmax = array[0];

  var currentmin = array[0];

  var overallmax = array[0];

  var overallmin = array[0];

  var i;

  for (i = 1; i < array.length; i++) {

    if (array[i] <= array[i - 1]) {

      // value is same or decreased

      currentmin = array[i];

    } else {

      // check if previous iteration was the largest

      if (currentmax - currentmin > overallmax - overallmin) {

        overallmax = currentmax;

        overallmin = currentmin;

      }

      // restart

      currentmax = array[i];

      currentmin = array[i];

    }

  }

  // check if last iteration was the largest

  if (currentmax - currentmin > overallmax - overallmin) {

    overallmax = currentmax;

    overallmin = currentmin;

  }



  return [overallmax, overallmin, overallmax - overallmin];

}

console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100, 90]));

console.log(checkData([10, 100, 50, 50, 10, 100, 50, 50, 1]));

edited Nov 26 at 15:16

answered Nov 26 at 13:36

Salman A

174k66334421

This fails for [100, 90, 80, 120, 200, 100 ,90]. The return must be max = 200, min = 90 and drop = 110
– Pommesloch
Nov 26 at 13:50

1

the logic is sound (I think) and i just need to update the max min everytime the values change. See revised answer.
– Salman A
Nov 26 at 13:55

add a comment |

up vote
2
down vote

You need to iterate the array once (O(n)) and keep a running count of min and max values and:

Reset it every time the value increases w.r.t. previous value

But note them down if the difference is greater than previously noted values

function checkData(array) {

  var currentmax = array[0];

  var currentmin = array[0];

  var overallmax = array[0];

  var overallmin = array[0];

  var i;

  for (i = 1; i < array.length; i++) {

    if (array[i] <= array[i - 1]) {

      // value is same or decreased

      currentmin = array[i];

    } else {

      // check if previous iteration was the largest

      if (currentmax - currentmin > overallmax - overallmin) {

        overallmax = currentmax;

        overallmin = currentmin;

      }

      // restart

      currentmax = array[i];

      currentmin = array[i];

    }

  }

  // check if last iteration was the largest

  if (currentmax - currentmin > overallmax - overallmin) {

    overallmax = currentmax;

    overallmin = currentmin;

  }



  return [overallmax, overallmin, overallmax - overallmin];

}

console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100, 90]));

console.log(checkData([10, 100, 50, 50, 10, 100, 50, 50, 1]));

edited Nov 26 at 15:16

answered Nov 26 at 13:36

Salman A

174k66334421

This fails for [100, 90, 80, 120, 200, 100 ,90]. The return must be max = 200, min = 90 and drop = 110
– Pommesloch
Nov 26 at 13:50

1

the logic is sound (I think) and i just need to update the max min everytime the values change. See revised answer.
– Salman A
Nov 26 at 13:55

add a comment |

up vote
2
down vote

You need to iterate the array once (O(n)) and keep a running count of min and max values and:

Reset it every time the value increases w.r.t. previous value

But note them down if the difference is greater than previously noted values

function checkData(array) {

  var currentmax = array[0];

  var currentmin = array[0];

  var overallmax = array[0];

  var overallmin = array[0];

  var i;

  for (i = 1; i < array.length; i++) {

    if (array[i] <= array[i - 1]) {

      // value is same or decreased

      currentmin = array[i];

    } else {

      // check if previous iteration was the largest

      if (currentmax - currentmin > overallmax - overallmin) {

        overallmax = currentmax;

        overallmin = currentmin;

      }

      // restart

      currentmax = array[i];

      currentmin = array[i];

    }

  }

  // check if last iteration was the largest

  if (currentmax - currentmin > overallmax - overallmin) {

    overallmax = currentmax;

    overallmin = currentmin;

  }



  return [overallmax, overallmin, overallmax - overallmin];

}

console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100, 90]));

console.log(checkData([10, 100, 50, 50, 10, 100, 50, 50, 1]));

edited Nov 26 at 15:16

answered Nov 26 at 13:36

Salman A

174k66334421

You need to iterate the array once (O(n)) and keep a running count of min and max values and:

Reset it every time the value increases w.r.t. previous value

But note them down if the difference is greater than previously noted values

function checkData(array) {

  var currentmax = array[0];

  var currentmin = array[0];

  var overallmax = array[0];

  var overallmin = array[0];

  var i;

  for (i = 1; i < array.length; i++) {

    if (array[i] <= array[i - 1]) {

      // value is same or decreased

      currentmin = array[i];

    } else {

      // check if previous iteration was the largest

      if (currentmax - currentmin > overallmax - overallmin) {

        overallmax = currentmax;

        overallmin = currentmin;

      }

      // restart

      currentmax = array[i];

      currentmin = array[i];

    }

  }

  // check if last iteration was the largest

  if (currentmax - currentmin > overallmax - overallmin) {

    overallmax = currentmax;

    overallmin = currentmin;

  }



  return [overallmax, overallmin, overallmax - overallmin];

}

console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100, 90]));

console.log(checkData([10, 100, 50, 50, 10, 100, 50, 50, 1]));

function checkData(array) {

  var currentmax = array[0];

  var currentmin = array[0];

  var overallmax = array[0];

  var overallmin = array[0];

  var i;

  for (i = 1; i < array.length; i++) {

    if (array[i] <= array[i - 1]) {

      // value is same or decreased

      currentmin = array[i];

    } else {

      // check if previous iteration was the largest

      if (currentmax - currentmin > overallmax - overallmin) {

        overallmax = currentmax;

        overallmin = currentmin;

      }

      // restart

      currentmax = array[i];

      currentmin = array[i];

    }

  }

  // check if last iteration was the largest

  if (currentmax - currentmin > overallmax - overallmin) {

    overallmax = currentmax;

    overallmin = currentmin;

  }



  return [overallmax, overallmin, overallmax - overallmin];

}

console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100, 90]));

console.log(checkData([10, 100, 50, 50, 10, 100, 50, 50, 1]));

function checkData(array) {

  var currentmax = array[0];

  var currentmin = array[0];

  var overallmax = array[0];

  var overallmin = array[0];

  var i;

  for (i = 1; i < array.length; i++) {

    if (array[i] <= array[i - 1]) {

      // value is same or decreased

      currentmin = array[i];

    } else {

      // check if previous iteration was the largest

      if (currentmax - currentmin > overallmax - overallmin) {

        overallmax = currentmax;

        overallmin = currentmin;

      }

      // restart

      currentmax = array[i];

      currentmin = array[i];

    }

  }

  // check if last iteration was the largest

  if (currentmax - currentmin > overallmax - overallmin) {

    overallmax = currentmax;

    overallmin = currentmin;

  }



  return [overallmax, overallmin, overallmax - overallmin];

}

console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100, 90]));

console.log(checkData([10, 100, 50, 50, 10, 100, 50, 50, 1]));

edited Nov 26 at 15:16

answered Nov 26 at 13:36

Salman A

174k66334421

edited Nov 26 at 15:16

answered Nov 26 at 13:36

Salman A

174k66334421

answered Nov 26 at 13:36

Salman A

174k66334421

answered Nov 26 at 13:36

Salman A

174k66334421

This fails for [100, 90, 80, 120, 200, 100 ,90]. The return must be max = 200, min = 90 and drop = 110
– Pommesloch
Nov 26 at 13:50

1

the logic is sound (I think) and i just need to update the max min everytime the values change. See revised answer.
– Salman A
Nov 26 at 13:55

add a comment |

This fails for [100, 90, 80, 120, 200, 100 ,90]. The return must be max = 200, min = 90 and drop = 110
– Pommesloch
Nov 26 at 13:50

1

the logic is sound (I think) and i just need to update the max min everytime the values change. See revised answer.
– Salman A
Nov 26 at 13:55

This fails for [100, 90, 80, 120, 200, 100 ,90]. The return must be max = 200, min = 90 and drop = 110
– Pommesloch
Nov 26 at 13:50

the logic is sound (I think) and i just need to update the max min everytime the values change. See revised answer.
– Salman A
Nov 26 at 13:55

add a comment |

up vote
0
down vote

You need to keep track of two things:

The maximum value you have up to an element i.

The minimum value you have from an element i to the end of the list.

Then you just need to find the drop for each index and select which one is biggest.

Here is the code:

function maxDrop (data) {

  if (!data || data.length === 0) {

    return;

  }

  const max = ;

  const min = ;

  for (let i = 0; i < data.length; i++) {

    const left = data.slice(0, i);

    const right = data.slice(i, data.length);

    max.push(Math.max.apply(null, left));

    min.push(Math.min.apply(null, right));

  }

  let maxDrop = max[0] - min[0];

  let maxValue = max[0];

  let minValue = min[0];

  for (let j = 0; j < data.length; j++) {

    const drop = max[j] - min[j];

    if (maxDrop < drop) {

      maxDrop = drop;

      maxValue = max[j];

      minValue = min[j];

    }

  }

  return [maxValue, minValue, maxDrop];

}



console.log(maxDrop([100,90,80,120]))

console.log(maxDrop([100,110,120,300,200,70,60,50,90,400]))

console.log(maxDrop([100,90,80,120,30]))

edited Nov 26 at 13:55

answered Nov 26 at 13:34

kakamg0

82649

This fails for [100, 90, 80, 120, 30]. The output is [100, 80, 20] but it should be [120, 30, 90].
– Ted Hopp
Nov 26 at 13:37

@TedHopp Fixed it, I was excluding the last element when searching for the minimum value. Thanks!
– kakamg0
Nov 26 at 13:56

add a comment |

up vote
0
down vote

You need to keep track of two things:

The maximum value you have up to an element i.

The minimum value you have from an element i to the end of the list.

Then you just need to find the drop for each index and select which one is biggest.

Here is the code:

function maxDrop (data) {

  if (!data || data.length === 0) {

    return;

  }

  const max = ;

  const min = ;

  for (let i = 0; i < data.length; i++) {

    const left = data.slice(0, i);

    const right = data.slice(i, data.length);

    max.push(Math.max.apply(null, left));

    min.push(Math.min.apply(null, right));

  }

  let maxDrop = max[0] - min[0];

  let maxValue = max[0];

  let minValue = min[0];

  for (let j = 0; j < data.length; j++) {

    const drop = max[j] - min[j];

    if (maxDrop < drop) {

      maxDrop = drop;

      maxValue = max[j];

      minValue = min[j];

    }

  }

  return [maxValue, minValue, maxDrop];

}



console.log(maxDrop([100,90,80,120]))

console.log(maxDrop([100,110,120,300,200,70,60,50,90,400]))

console.log(maxDrop([100,90,80,120,30]))

edited Nov 26 at 13:55

answered Nov 26 at 13:34

kakamg0

82649

This fails for [100, 90, 80, 120, 30]. The output is [100, 80, 20] but it should be [120, 30, 90].
– Ted Hopp
Nov 26 at 13:37

@TedHopp Fixed it, I was excluding the last element when searching for the minimum value. Thanks!
– kakamg0
Nov 26 at 13:56

add a comment |

up vote
0
down vote

You need to keep track of two things:

The maximum value you have up to an element i.

The minimum value you have from an element i to the end of the list.

Then you just need to find the drop for each index and select which one is biggest.

Here is the code:

function maxDrop (data) {

  if (!data || data.length === 0) {

    return;

  }

  const max = ;

  const min = ;

  for (let i = 0; i < data.length; i++) {

    const left = data.slice(0, i);

    const right = data.slice(i, data.length);

    max.push(Math.max.apply(null, left));

    min.push(Math.min.apply(null, right));

  }

  let maxDrop = max[0] - min[0];

  let maxValue = max[0];

  let minValue = min[0];

  for (let j = 0; j < data.length; j++) {

    const drop = max[j] - min[j];

    if (maxDrop < drop) {

      maxDrop = drop;

      maxValue = max[j];

      minValue = min[j];

    }

  }

  return [maxValue, minValue, maxDrop];

}



console.log(maxDrop([100,90,80,120]))

console.log(maxDrop([100,110,120,300,200,70,60,50,90,400]))

console.log(maxDrop([100,90,80,120,30]))

edited Nov 26 at 13:55

answered Nov 26 at 13:34

kakamg0

82649

You need to keep track of two things:

The maximum value you have up to an element i.

The minimum value you have from an element i to the end of the list.

Then you just need to find the drop for each index and select which one is biggest.

Here is the code:

function maxDrop (data) {

  if (!data || data.length === 0) {

    return;

  }

  const max = ;

  const min = ;

  for (let i = 0; i < data.length; i++) {

    const left = data.slice(0, i);

    const right = data.slice(i, data.length);

    max.push(Math.max.apply(null, left));

    min.push(Math.min.apply(null, right));

  }

  let maxDrop = max[0] - min[0];

  let maxValue = max[0];

  let minValue = min[0];

  for (let j = 0; j < data.length; j++) {

    const drop = max[j] - min[j];

    if (maxDrop < drop) {

      maxDrop = drop;

      maxValue = max[j];

      minValue = min[j];

    }

  }

  return [maxValue, minValue, maxDrop];

}



console.log(maxDrop([100,90,80,120]))

console.log(maxDrop([100,110,120,300,200,70,60,50,90,400]))

console.log(maxDrop([100,90,80,120,30]))

function maxDrop (data) {

  if (!data || data.length === 0) {

    return;

  }

  const max = ;

  const min = ;

  for (let i = 0; i < data.length; i++) {

    const left = data.slice(0, i);

    const right = data.slice(i, data.length);

    max.push(Math.max.apply(null, left));

    min.push(Math.min.apply(null, right));

  }

  let maxDrop = max[0] - min[0];

  let maxValue = max[0];

  let minValue = min[0];

  for (let j = 0; j < data.length; j++) {

    const drop = max[j] - min[j];

    if (maxDrop < drop) {

      maxDrop = drop;

      maxValue = max[j];

      minValue = min[j];

    }

  }

  return [maxValue, minValue, maxDrop];

}



console.log(maxDrop([100,90,80,120]))

console.log(maxDrop([100,110,120,300,200,70,60,50,90,400]))

console.log(maxDrop([100,90,80,120,30]))

function maxDrop (data) {

  if (!data || data.length === 0) {

    return;

  }

  const max = ;

  const min = ;

  for (let i = 0; i < data.length; i++) {

    const left = data.slice(0, i);

    const right = data.slice(i, data.length);

    max.push(Math.max.apply(null, left));

    min.push(Math.min.apply(null, right));

  }

  let maxDrop = max[0] - min[0];

  let maxValue = max[0];

  let minValue = min[0];

  for (let j = 0; j < data.length; j++) {

    const drop = max[j] - min[j];

    if (maxDrop < drop) {

      maxDrop = drop;

      maxValue = max[j];

      minValue = min[j];

    }

  }

  return [maxValue, minValue, maxDrop];

}



console.log(maxDrop([100,90,80,120]))

console.log(maxDrop([100,110,120,300,200,70,60,50,90,400]))

console.log(maxDrop([100,90,80,120,30]))

edited Nov 26 at 13:55

answered Nov 26 at 13:34

kakamg0

82649

edited Nov 26 at 13:55

answered Nov 26 at 13:34

kakamg0

82649

answered Nov 26 at 13:34

kakamg0

82649

answered Nov 26 at 13:34

kakamg0

82649

This fails for [100, 90, 80, 120, 30]. The output is [100, 80, 20] but it should be [120, 30, 90].
– Ted Hopp
Nov 26 at 13:37

@TedHopp Fixed it, I was excluding the last element when searching for the minimum value. Thanks!
– kakamg0
Nov 26 at 13:56

add a comment |

This fails for [100, 90, 80, 120, 30]. The output is [100, 80, 20] but it should be [120, 30, 90].
– Ted Hopp
Nov 26 at 13:37

@TedHopp Fixed it, I was excluding the last element when searching for the minimum value. Thanks!
– kakamg0
Nov 26 at 13:56

This fails for [100, 90, 80, 120, 30]. The output is [100, 80, 20] but it should be [120, 30, 90].
– Ted Hopp
Nov 26 at 13:37

@TedHopp Fixed it, I was excluding the last element when searching for the minimum value. Thanks!
– kakamg0
Nov 26 at 13:56

add a comment |

up vote
0
down vote

To add one more to the mix..
A possible approach is to create all the drop - ranges first, than get the one with the largest drop

A version with reduce:

function checkData(data) {

let dropInd = 1,

  	mx = data.reduce((arr,val, ind) => {

 if(ind && val > data[ind-1])dropInd++;  	      

 arr[dropInd] = arr[dropInd] || {max:val};

 arr[dropInd].min = val;

 arr[dropInd].drop = arr[dropInd].max - val;

 return arr;

}, ) //after reduce, islands are created based on 'dropInd'  

  .sort((v1,v2)=>v2.drop - v1.drop) //sort by drop descending

  [0]; //the first value now contains the maximum drop  



  return [mx.max,mx.min,mx.drop];

}







console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100 ,90]));

console.log(checkData([200,100, 90, 80, 120,  100 ,90]));

console.log(checkData([200,120,190, 90, 80, 120,  100 ,90]));

edited Nov 26 at 16:17

answered Nov 26 at 14:12

Me.Name

10.1k22039

add a comment |

up vote
0
down vote

To add one more to the mix..
A possible approach is to create all the drop - ranges first, than get the one with the largest drop

A version with reduce:

function checkData(data) {

let dropInd = 1,

  	mx = data.reduce((arr,val, ind) => {

 if(ind && val > data[ind-1])dropInd++;  	      

 arr[dropInd] = arr[dropInd] || {max:val};

 arr[dropInd].min = val;

 arr[dropInd].drop = arr[dropInd].max - val;

 return arr;

}, ) //after reduce, islands are created based on 'dropInd'  

  .sort((v1,v2)=>v2.drop - v1.drop) //sort by drop descending

  [0]; //the first value now contains the maximum drop  



  return [mx.max,mx.min,mx.drop];

}







console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100 ,90]));

console.log(checkData([200,100, 90, 80, 120,  100 ,90]));

console.log(checkData([200,120,190, 90, 80, 120,  100 ,90]));

edited Nov 26 at 16:17

answered Nov 26 at 14:12

Me.Name

10.1k22039

add a comment |

up vote
0
down vote

To add one more to the mix..
A possible approach is to create all the drop - ranges first, than get the one with the largest drop

A version with reduce:

function checkData(data) {

let dropInd = 1,

  	mx = data.reduce((arr,val, ind) => {

 if(ind && val > data[ind-1])dropInd++;  	      

 arr[dropInd] = arr[dropInd] || {max:val};

 arr[dropInd].min = val;

 arr[dropInd].drop = arr[dropInd].max - val;

 return arr;

}, ) //after reduce, islands are created based on 'dropInd'  

  .sort((v1,v2)=>v2.drop - v1.drop) //sort by drop descending

  [0]; //the first value now contains the maximum drop  



  return [mx.max,mx.min,mx.drop];

}







console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100 ,90]));

console.log(checkData([200,100, 90, 80, 120,  100 ,90]));

console.log(checkData([200,120,190, 90, 80, 120,  100 ,90]));

edited Nov 26 at 16:17

answered Nov 26 at 14:12

Me.Name

10.1k22039

To add one more to the mix..
A possible approach is to create all the drop - ranges first, than get the one with the largest drop

A version with reduce:

function checkData(data) {

let dropInd = 1,

  	mx = data.reduce((arr,val, ind) => {

 if(ind && val > data[ind-1])dropInd++;  	      

 arr[dropInd] = arr[dropInd] || {max:val};

 arr[dropInd].min = val;

 arr[dropInd].drop = arr[dropInd].max - val;

 return arr;

}, ) //after reduce, islands are created based on 'dropInd'  

  .sort((v1,v2)=>v2.drop - v1.drop) //sort by drop descending

  [0]; //the first value now contains the maximum drop  



  return [mx.max,mx.min,mx.drop];

}







console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100 ,90]));

console.log(checkData([200,100, 90, 80, 120,  100 ,90]));

console.log(checkData([200,120,190, 90, 80, 120,  100 ,90]));

function checkData(data) {

let dropInd = 1,

  	mx = data.reduce((arr,val, ind) => {

 if(ind && val > data[ind-1])dropInd++;  	      

 arr[dropInd] = arr[dropInd] || {max:val};

 arr[dropInd].min = val;

 arr[dropInd].drop = arr[dropInd].max - val;

 return arr;

}, ) //after reduce, islands are created based on 'dropInd'  

  .sort((v1,v2)=>v2.drop - v1.drop) //sort by drop descending

  [0]; //the first value now contains the maximum drop  



  return [mx.max,mx.min,mx.drop];

}







console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100 ,90]));

console.log(checkData([200,100, 90, 80, 120,  100 ,90]));

console.log(checkData([200,120,190, 90, 80, 120,  100 ,90]));

function checkData(data) {

let dropInd = 1,

  	mx = data.reduce((arr,val, ind) => {

 if(ind && val > data[ind-1])dropInd++;  	      

 arr[dropInd] = arr[dropInd] || {max:val};

 arr[dropInd].min = val;

 arr[dropInd].drop = arr[dropInd].max - val;

 return arr;

}, ) //after reduce, islands are created based on 'dropInd'  

  .sort((v1,v2)=>v2.drop - v1.drop) //sort by drop descending

  [0]; //the first value now contains the maximum drop  



  return [mx.max,mx.min,mx.drop];

}







console.log(checkData([100, 90, 80, 120]));

console.log(checkData([100, 90, 80, 120, 200, 100 ,90]));

console.log(checkData([200,100, 90, 80, 120,  100 ,90]));

console.log(checkData([200,120,190, 90, 80, 120,  100 ,90]));

edited Nov 26 at 16:17

answered Nov 26 at 14:12

Me.Name

10.1k22039

edited Nov 26 at 16:17

answered Nov 26 at 14:12

Me.Name

10.1k22039

answered Nov 26 at 14:12

Me.Name

10.1k22039

answered Nov 26 at 14:12

Me.Name

10.1k22039

add a comment |

up vote
-1
down vote

This works exactly as intended (as per your expected output), as shown in the following code snippet.

The issue must be in how you are sending your data as an array.

alert(checkData([100, 90, 80, 120]));



function checkData(data) {

  let max = 0

  let min = 0

  let drop = 0



  for (let i = 0; i < data.length; i++) {

    if (max < data[i]) {

      max = data[i] //?

    } else {

      let tempDrop = max - data[i]

      drop = Math.max(tempDrop)

      min = max - drop

    }

  }

  return [max, min, drop]

}

// Output : 120, 80, 20

However, if what you are looking for is a Max, a Min, and then the biggest difference, i.e. between the the max and min, which in your given example would be 40, then you can simply do this.

alert(checkData([100, 90, 80, 120]));



function checkData(data) {



  let max = data.reduce(function(a, b) {

    return Math.max(a, b);

  });

  let min = data.reduce(function(a, b) {

    return Math.min(a, b);

  });



  let drop = max-min;



  return [max, min, drop];

  

}

// Output : 120, 80, 40

I only mention this as I don't know why you've said you expect the biggest difference to be 20, given 100 and 80, when you have 120 and 80 in the same array, meaning the biggest difference is 40.

edited Nov 26 at 13:01

answered Nov 26 at 12:50

cmprogram

1,063519

Thanks, but the correct return must be max = 100, min = 80 and drop = 20. Look at the graphic that I added to my post
– Pommesloch
Nov 26 at 13:11

But 100 isn't the max... If you don't want the 120 to be included, just don't include it in the array...
– cmprogram
Nov 26 at 13:13

This data comes from a shares API. That is why I need this chronological from left to right delta. The shares course is crashed here from 100 to 80. This is a -20% drop. In my attempt, I miss the chronological aspect
– Pommesloch
Nov 26 at 13:18

1

OP wants the max and min associated with the largest drop, where a drop is a sequence of descending data values. The largest drop is from 100 to 80 (indexes 0 through 2).
– Ted Hopp
Nov 26 at 13:34

add a comment |

up vote
-1
down vote

This works exactly as intended (as per your expected output), as shown in the following code snippet.

The issue must be in how you are sending your data as an array.

alert(checkData([100, 90, 80, 120]));



function checkData(data) {

  let max = 0

  let min = 0

  let drop = 0



  for (let i = 0; i < data.length; i++) {

    if (max < data[i]) {

      max = data[i] //?

    } else {

      let tempDrop = max - data[i]

      drop = Math.max(tempDrop)

      min = max - drop

    }

  }

  return [max, min, drop]

}

// Output : 120, 80, 20

However, if what you are looking for is a Max, a Min, and then the biggest difference, i.e. between the the max and min, which in your given example would be 40, then you can simply do this.

alert(checkData([100, 90, 80, 120]));



function checkData(data) {



  let max = data.reduce(function(a, b) {

    return Math.max(a, b);

  });

  let min = data.reduce(function(a, b) {

    return Math.min(a, b);

  });



  let drop = max-min;



  return [max, min, drop];

  

}

// Output : 120, 80, 40

I only mention this as I don't know why you've said you expect the biggest difference to be 20, given 100 and 80, when you have 120 and 80 in the same array, meaning the biggest difference is 40.

edited Nov 26 at 13:01

answered Nov 26 at 12:50

cmprogram

1,063519

Thanks, but the correct return must be max = 100, min = 80 and drop = 20. Look at the graphic that I added to my post
– Pommesloch
Nov 26 at 13:11

But 100 isn't the max... If you don't want the 120 to be included, just don't include it in the array...
– cmprogram
Nov 26 at 13:13

This data comes from a shares API. That is why I need this chronological from left to right delta. The shares course is crashed here from 100 to 80. This is a -20% drop. In my attempt, I miss the chronological aspect
– Pommesloch
Nov 26 at 13:18

1

OP wants the max and min associated with the largest drop, where a drop is a sequence of descending data values. The largest drop is from 100 to 80 (indexes 0 through 2).
– Ted Hopp
Nov 26 at 13:34

add a comment |

up vote
-1
down vote

This works exactly as intended (as per your expected output), as shown in the following code snippet.

The issue must be in how you are sending your data as an array.

alert(checkData([100, 90, 80, 120]));



function checkData(data) {

  let max = 0

  let min = 0

  let drop = 0



  for (let i = 0; i < data.length; i++) {

    if (max < data[i]) {

      max = data[i] //?

    } else {

      let tempDrop = max - data[i]

      drop = Math.max(tempDrop)

      min = max - drop

    }

  }

  return [max, min, drop]

}

// Output : 120, 80, 20

However, if what you are looking for is a Max, a Min, and then the biggest difference, i.e. between the the max and min, which in your given example would be 40, then you can simply do this.

alert(checkData([100, 90, 80, 120]));



function checkData(data) {



  let max = data.reduce(function(a, b) {

    return Math.max(a, b);

  });

  let min = data.reduce(function(a, b) {

    return Math.min(a, b);

  });



  let drop = max-min;



  return [max, min, drop];

  

}

// Output : 120, 80, 40

I only mention this as I don't know why you've said you expect the biggest difference to be 20, given 100 and 80, when you have 120 and 80 in the same array, meaning the biggest difference is 40.

edited Nov 26 at 13:01

answered Nov 26 at 12:50

cmprogram

1,063519

This works exactly as intended (as per your expected output), as shown in the following code snippet.

The issue must be in how you are sending your data as an array.

alert(checkData([100, 90, 80, 120]));



function checkData(data) {

  let max = 0

  let min = 0

  let drop = 0



  for (let i = 0; i < data.length; i++) {

    if (max < data[i]) {

      max = data[i] //?

    } else {

      let tempDrop = max - data[i]

      drop = Math.max(tempDrop)

      min = max - drop

    }

  }

  return [max, min, drop]

}

// Output : 120, 80, 20

However, if what you are looking for is a Max, a Min, and then the biggest difference, i.e. between the the max and min, which in your given example would be 40, then you can simply do this.

alert(checkData([100, 90, 80, 120]));



function checkData(data) {



  let max = data.reduce(function(a, b) {

    return Math.max(a, b);

  });

  let min = data.reduce(function(a, b) {

    return Math.min(a, b);

  });



  let drop = max-min;



  return [max, min, drop];

  

}

// Output : 120, 80, 40

I only mention this as I don't know why you've said you expect the biggest difference to be 20, given 100 and 80, when you have 120 and 80 in the same array, meaning the biggest difference is 40.

alert(checkData([100, 90, 80, 120]));



function checkData(data) {

  let max = 0

  let min = 0

  let drop = 0



  for (let i = 0; i < data.length; i++) {

    if (max < data[i]) {

      max = data[i] //?

    } else {

      let tempDrop = max - data[i]

      drop = Math.max(tempDrop)

      min = max - drop

    }

  }

  return [max, min, drop]

}

alert(checkData([100, 90, 80, 120]));



function checkData(data) {

  let max = 0

  let min = 0

  let drop = 0



  for (let i = 0; i < data.length; i++) {

    if (max < data[i]) {

      max = data[i] //?

    } else {

      let tempDrop = max - data[i]

      drop = Math.max(tempDrop)

      min = max - drop

    }

  }

  return [max, min, drop]

}

alert(checkData([100, 90, 80, 120]));



function checkData(data) {



  let max = data.reduce(function(a, b) {

    return Math.max(a, b);

  });

  let min = data.reduce(function(a, b) {

    return Math.min(a, b);

  });



  let drop = max-min;



  return [max, min, drop];

  

}

alert(checkData([100, 90, 80, 120]));



function checkData(data) {



  let max = data.reduce(function(a, b) {

    return Math.max(a, b);

  });

  let min = data.reduce(function(a, b) {

    return Math.min(a, b);

  });



  let drop = max-min;



  return [max, min, drop];

  

}

edited Nov 26 at 13:01

answered Nov 26 at 12:50

cmprogram

1,063519

edited Nov 26 at 13:01

answered Nov 26 at 12:50

cmprogram

1,063519

answered Nov 26 at 12:50

cmprogram

1,063519

answered Nov 26 at 12:50

cmprogram

1,063519

Thanks, but the correct return must be max = 100, min = 80 and drop = 20. Look at the graphic that I added to my post
– Pommesloch
Nov 26 at 13:11

But 100 isn't the max... If you don't want the 120 to be included, just don't include it in the array...
– cmprogram
Nov 26 at 13:13

This data comes from a shares API. That is why I need this chronological from left to right delta. The shares course is crashed here from 100 to 80. This is a -20% drop. In my attempt, I miss the chronological aspect
– Pommesloch
Nov 26 at 13:18

1

OP wants the max and min associated with the largest drop, where a drop is a sequence of descending data values. The largest drop is from 100 to 80 (indexes 0 through 2).
– Ted Hopp
Nov 26 at 13:34

add a comment |

Thanks, but the correct return must be max = 100, min = 80 and drop = 20. Look at the graphic that I added to my post
– Pommesloch
Nov 26 at 13:11

But 100 isn't the max... If you don't want the 120 to be included, just don't include it in the array...
– cmprogram
Nov 26 at 13:13

This data comes from a shares API. That is why I need this chronological from left to right delta. The shares course is crashed here from 100 to 80. This is a -20% drop. In my attempt, I miss the chronological aspect
– Pommesloch
Nov 26 at 13:18

1

OP wants the max and min associated with the largest drop, where a drop is a sequence of descending data values. The largest drop is from 100 to 80 (indexes 0 through 2).
– Ted Hopp
Nov 26 at 13:34

Thanks, but the correct return must be max = 100, min = 80 and drop = 20. Look at the graphic that I added to my post
– Pommesloch
Nov 26 at 13:11

But 100 isn't the max... If you don't want the 120 to be included, just don't include it in the array...
– cmprogram
Nov 26 at 13:13

This data comes from a shares API. That is why I need this chronological from left to right delta. The shares course is crashed here from 100 to 80. This is a -20% drop. In my attempt, I miss the chronological aspect
– Pommesloch
Nov 26 at 13:18

OP wants the max and min associated with the largest drop, where a drop is a sequence of descending data values. The largest drop is from 100 to 80 (indexes 0 through 2).
– Ted Hopp
Nov 26 at 13:34

add a comment |

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