Unexpected return during algorithm challenge

JavaScript
#1

Hello all I am working on this challenge:

https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-algorithm-scripting/return-largest-numbers-in-arrays

and I have been able to get the code to return an array, but it is filled with the two highest numbers of each sub-array rather than just the single highest number. my code follows:

function largestOfFour(arr) {
  
  let sorted = [];
  for (let i = 0; i < arr.length; i++) {
    let arrInner = arr[i];
    for (let  j = 0; j < arrInner.length; j++) {
      sorted.push(arrInner.sort().pop());
    }
  } return sorted;
}

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

so I am getting [5,4,27,26,39,37,857,1001] rather than [5, 27, 39, 1001].

Any help is greatly appreciated!

#2

I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make easier to read.

See this post to find the backtick on your keyboard. The “preformatted text” tool in the editor (</>) will also add backticks around text.

Note: Backticks are not single quotes.

markdown_Forums

#3

How are you testing to make sure that the number you are adding to the array is the largest?

#4
  1. If it were not for the fact that you changed the length of the innerArray (by pop) you would just get the full array back in sorted order.

Removing the inner loop:

function largestOfFour(arr) {
  
  let sorted = [];
  for (let i = 0; i < arr.length; i++) {
    let arrInner = arr[i];
    sorted.push(arrInner.sort().pop());
  }
  return sorted;
}

Returns: [5, 27, 39, 857]
  1. Sorting the last array is not giving you what you want.
[1000, 1001, 857, 1].sort().pop()
Returns: 857
#5

Hey I figured it out, thanks for cluing me in on that unnecessary inner loop! That really got the ball rolling. I ended up running a function inside of sort() as follows:

 sorted.push(arrInner.sort(function( a, b) {return a - b}).pop());

This “sorted” (pun totally intended) the rest of the code out and now it is working. Thanks all for your input!

#6