Find indexes of the biggest and lowest numbers in array

Question

I need to create a function which finds the two numbers with the largest difference between them and returns their indices as an array of two elements - [ lowest, biggest ].

Notice: the bigger number must be to the right from lowest. If we have no difference between the numbers, the function must return [].

function getProfit(arr) {
    let result = [];
    let sortedArr = arr.sort();
    let min = sortedArr.indexOf(Math.min(...sortedArr));
    let max = sortedArr.indexOf(Math.max(...sortedArr));
    if(max > min) {
        result.push(min);
        result.push(max);
        return result;
    } else {
        return [];
    }

}

console.log(getProfit([13, 6, 3, 4, 10, 2, 3], [2, 4]));

This is the array of indexes of the number with the biggest difference — RuddaTriduba, Aug 16 '21 at 06:29
`getProfit` take one parameter but you pass two prams? also when the array is sorted ascending first position is lowest and last position is biggest! — Alireza Ahmadi, Aug 16 '21 at 06:32
Why do you pass two arrays to the function? What's the expected result of the given code? — jabaa, Aug 16 '21 at 06:34
Also note that `By default, the sort method sorts elements alphabetically` so you need to sort numerically so use this one: `arr.sort(function (a, b) {return a - b;});` — Alireza Ahmadi, Aug 16 '21 at 06:38
Is `getProfit([13, 6, 3, 4, 10, 2, 3], [2, 4])` the unit test? Is `[2, 4]` the expected result of input `[13, 6, 3, 4, 10, 2, 3]`? — jabaa, Aug 16 '21 at 06:54
Yes, this is unit test. Do I need to use assertion? [2, 4] is indexes of numbers with the biggest difference — RuddaTriduba, Aug 16 '21 at 06:59

Daniel · Accepted Answer · 2021-08-16T07:04:49.043

2

You need to iterate through the list with two pointers (indexes) left and right as described below: you will accomplish your solution with time complexity of O(n).

function getProfit(arr) {
    let result = [0,0];
    for(let l=0,r=0; l<arr.length-1 && r<arr.length-1;r++){
        if(arr[l] > arr[r]){
            l++;
        }else if(arr[r]-arr[l]> arr[result[1]]-arr[result[0]]){
            result[0] = l;
            result[1] = r;
        }
    }
    return (result[1] === 0) ? [] : result;
}

console.log(getProfit([13, 6, 3, 4, 10, 2, 3]));

edited Aug 16 '21 at 07:04

answered Aug 16 '21 at 06:59

Daniel

1,895
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20

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Wow... I tried to use the brute force with for() -> for()... I will remember it, thanks! – RuddaTriduba Aug 16 '21 at 07:06
@RuddaTriduba The function `getProfit` need to have two arguments right? – Nitheesh Aug 16 '21 at 07:12
@Nitheesh no, the function get one argument as input array and it must return another – RuddaTriduba Aug 16 '21 at 07:20

Find indexes of the biggest and lowest numbers in array

1 Answers1