Algorithm Scripting easy level

JavaScript
1

Hey all. I’m sure this has been answered but I don’t want to just look up an answer. I was hoping some kind soul will walk me through this to help me learn!

I am currently working on these algorithm scripting exercises, and like many. I feel like the cirriculum went from 0-100 quick and i’m just lost. I am trying to get the largest within the array of arrays in this problem. I am getting NaN and am confused as to why.

function largestOfFour(arr) {
  let maxArray = []
  for(let i = 0; i < arr.length; i++){
      console.log(arr[i]);
      maxArray.push(Math.max(arr[i]));
  }
  return maxArray; 
}

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

My thought process is, I do a for loop to go through each item of these arrays, and then use Math.max through each index of the array and push that Max number into a new array of it’s own and return the result. What would be the most logical step to get better at this insane algorithm scripting? Thank you guys !

2

Look at the documentation for Math.max:

It doesn’t take an array as an argument, the numbers need to be passed in as seperate arguments (the docs show a solution for this)

3

@DanCouper thanks man. Okay so I use the spread operator which shows the max of all the arrays, but the challenge is asking me to I guess pick the largest array out of all the arrays? If I understand this challenge correctly. Thanks for the help thus far.

4

Nono, so it’s asking you to return an array made up of the highest number for each of the sub-arrays. So if you have

[
  [1,2,3],
  [4,5,6],
  [7,8,9],
  [10,11,12],
]

You would return

[3, 6, 9, 12]

You don’t need to find the overall maximum – you only need to make one small addition to your existing code (fix that Math.max call by using the spread operator to turn an array of numbers into individual arguments)

5

Not quite sure I understand. If I use spread I get a giant array of all indices of the array of arrays:

function largestOfFour(arr) {
  let maxArray = []
  for(let i = 0; i < arr.length; i++){
      console.log(arr[i]);
        maxArray.push(...arr[i])
      }
      return maxArray;
  }
   

console.log(largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], 
  [32, 35, 37, 39], [1000, 1001, 857, 1]]));
6

well, you do not have Math.max anymore

you are giving multiple arguments to push, and the method is adding them all as you said to do