Basic Algorithm Scripting: Return Largest Numbers in Arrays (JavaScript) [duplicate]

Question

I'm supposed to be returning an array consisting of the largest number from each sub-array. Here is my code:

function largestOfFour(arr) {
  let largestNum = [0,0,0,0];
  for (let i = 0; i < arr.length; i++) {
    for (let j = 0; j < arr[i].length; j++) {
      if (arr[i][j] > largestNum[i]) {
        largestNum[i] = arr[i][j];
      }
    }
  }
  return largestNum;
}

largestOfFour([[4, 5, 1, 3],[13, 27, 18, 26],[32, 35, 37, 39],[1000, 1001, 857, 1]]);

I pass all the tests except for one.

largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]])

should return an array. Passed

largestOfFour([[13, 27, 18, 26], [4, 5, 1, 3], [32, 35, 37, 39], [1000, 1001, 857, 1]])

should return [27, 5, 39, 1001]. Passed

largestOfFour([[4, 9, 1, 3], [13, 35, 18, 26], [32, 35, 97, 39], [1000000, 1001, 857, 1]])

should return [9, 35, 97, 1000000].

largestOfFour([[17, 23, 25, 12], [25, 7, 34, 48], [4, -10, 18, 21], [-72, -3, -17, -10]])

should return [25, 48, 21, -3]. Failed

If anyone would be willing to tell me what i'm doing wrong, that would be so helpful. Thank you

because largestNum has 0's as min values, but values could be negative as well, thus your assumption that 0 is the min. value is incorrect . — Lyubomir
– Lyubomir, Commented Aug 21, 2018 at 14:05
in negative smaller one is the largest. -1 is the largest number in negative — Sridhar Rajan
– Sridhar Rajan, Commented Aug 21, 2018 at 14:07

Luca Kiebel · Accepted Answer · 2018-08-21 14:05:49Z

1

You can simply use Math.max on each of the sub arrays by deconstructing them:

function largestOfFour(arr) {
  return arr.map(subarr => Math.max(...subarr));
}

console.log(largestOfFour([[4, 5, 1, 3],[13, 27, 18, 26],[32, 35, 37, 39],[1000, 1001, 857, 1]]));

console.log(largestOfFour([[17, 23, 25, 12], [25, 7, 34, 48], [4, -10, 18, 21], [-72, -3, -17, -10]]));

answered Aug 21, 2018 at 14:05

Luca Kiebel

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