how to return the lowest index of the array?

Question

For example, getIndexToIns([1,2,3,4], 1.5) should return 1 because it is greater than 1 (index 0), but less than 2 (index 1).

Likewise, getIndexToIns([20,3,5], 19) should return 2 because once the array has been sorted it will look like [3,5,20] and 19 is less than 20 (index 2) and greater than 5 (index 1).

this is my code

function getIndexToIns(arr, num) {
  // Find my place in this sorted array.
  arr = arr.sort();
  num = Math.floor(num);
  for(let i=0;i<arr.length;i++){
  }
  return num;
}

getIndexToIns([690, 60], 59);

What have you tried? What if the number is less than all in the array? Simplest IMO would be to if (arr[i] > num) return i - 1; in your loop, which returns -1 if num is less than all the entries. — Drew Reese
– Drew Reese, Commented Jan 2, 2020 at 4:51

Nick Parsons · Accepted Answer · 2020-01-02 05:02:16Z

6

You can use .findIndex() to find the first element in your sorted array which is larger than your passed num element:

const getIndexToIns = (arr, num) => {
  const res = arr.sort((a, b) => a-b).findIndex(n => n > num);
  return res === -1 ? arr.length : res;
}

console.log(getIndexToIns([1,2,3,4], 1.5));
console.log(getIndexToIns([20,3,5], 19));
console.log(getIndexToIns([20,3,5], 100)); // 3 (array length)

edited Jan 2, 2020 at 5:02

answered Jan 2, 2020 at 4:53

Nick Parsons

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3 Comments

Mark Over a year ago

Checking for -1 from findIndex() and returning the array length might be a nice touch.

Nick Parsons Over a year ago

@MarkMeyer nice idea, I've added that in

adiga Over a year ago

@RushikeshGanesh If the answer resolved your issue, please mark it as accepted by clicking on the grey checkmark on the left

adiga · Accepted Answer · 2020-01-02 05:51:55Z

1

Here the solution

function getIndexToIns(arr, num) {
  var counter = 0;
  // Find my place in this sorted array.
  arr = arr.sort();
  num = Math.floor(num);

  for (let i = 0; i < arr.length; i++) {
    if (num > arr[i]) {
      counter++
    } else {
      break;
    }
  }
  return counter;
}

var count = getIndexToIns([690, 60, 55, 2], 59);
console.log(count);

edited Jan 2, 2020 at 5:51

adiga

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answered Jan 2, 2020 at 4:50

saifur

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Comments

Rahul Bharadwaj · Accepted Answer · 2020-01-02 04:47:27Z

0

This is like one small part of insertion sort (which you can read about here). What you are trying to do is to just compare the num with each element of sorted array arr, until you find a number which is greater than num.

So it'd look something like this:

for(let i=0;i<arr.length;i++){
    if(num <= arr[i])
        return i;
}

answered Jan 2, 2020 at 4:47

Rahul Bharadwaj

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Comments

Omkar Shete · Accepted Answer · 2020-01-02 04:56:00Z

0

function getIndexToIns(arr, num) {
    var return_val;
  // Find my place in this sorted array.
  arr = arr.sort();
  num = Math.floor(num);
  for(let i=0;i<arr.length;i++){
    if(arr[i]>num){
        return_val = arr[i-1];
    }
  }
 return return_val;
}

var return_value = getIndexToIns([690, 60], 59);
console.log(return_value);

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

answered Jan 2, 2020 at 4:56

Omkar Shete

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Comments

adiga · Accepted Answer · 2020-01-02 05:51:25Z

0

Try this

function getIndexToIns(arr, num) {
  // Find my place in this sorted array.
  var index = 0
  arr.sort((a, b) => a - b)
  for (let i = 0; i < arr.length; i++) {
    if (num > arr[i]) {

    } else {
      index = i
      break
    }
  }
  return index;
}

console.log(
  getIndexToIns([1, 2, 3, 4], 1.5)
)

edited Jan 2, 2020 at 5:51

adiga

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answered Jan 2, 2020 at 5:04

Passionate Coder

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Comments

adiga · Accepted Answer · 2020-01-02 05:52:31Z

0

here is a code you may try

function getIndexToIns(a, b) {
  let ind = 0;
  for (var i = 0; i < a.length; i++) {
    if (b < a[i]) {
      ind++;
    }
  }
  return ind
}

console.log(getIndexToIns([20, 3, 5], 19));

edited Jan 2, 2020 at 5:52

adiga

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answered Jan 2, 2020 at 4:54

Alex

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Comments

adiga · Accepted Answer · 2020-01-02 06:50:55Z

0

Because arr.sort() sorting does not sort the array accurately, check this: Array.sort() doesn't sort numbers correctly

This code is working fine

function getIndexToIns(arr, num) {
  // Find my place in this sorted array.
  arr.sort(function(a, b) { return a - b; });
  num = Math.floor(num);
  //console.log(arr)
  var found = arr.findIndex(function(e) {
    return e > num;
  });
  return found;
}

console.log(
  getIndexToIns([1, 2, 3, 4], 1.5),
  getIndexToIns([20, 3, 5], 19),
  getIndexToIns([20, 3, 5], 19)
)

edited Jan 2, 2020 at 6:50

adiga

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answered Jan 2, 2020 at 5:00

Mohamad A Sallal

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