Basic Algorithm Scripting: Return Largest Number in Arrays

JavaScript
1

I believe there’s a concept I’m not getting 'coz I really think this should work. Please help me understand what I’m missing. I already looked at the solution and I think the difference is where I placed my variables and the return statement. TIA!

function largestOfFour(arr) {
  // You can do this!
  let maxNumber = 0;
  let newArr = [];

  for (let i = 0; i < arr.length; i++) {
    
    for (let x = 0; x < arr[i].length; x++){
      
      if(arr[i][x] > maxNumber) {
        maxNumber = arr[i][x];
        newArr = arr[i];
      }
    } 
  }

  return newArr;
}

largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]);
2

Put maxNumber between loops. Also you don’t need to assign value to newArray. You must to push it.
Your fixed code:

function largestOfFour(arr) {
  // You can do this!
 let newArr = [];

  for (let i = 0; i < arr.length; i++) {
 	
  	let maxNumber = 0;
    
    for (let x = 0; x < arr[i].length; x++){
      
      if(arr[i][x] > maxNumber) {
        maxNumber = arr[i][x];
        
      }
    } 
newArr.push(maxNumber);
	
  }
  return newArr;
}

But i have question for you. What will happen if you have array with arrays which contains only negative numbers ? :slight_smile:

1 Like
3

I just realized, I’m not understanding the problem correctly. I was trying to get the array with the highest number, but I am supposed to get the highest numbers of each array into an array. I thought the problem was like the previous the challenge. I’ll try this again.

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4

there is a function called Math.max() in javascript this might help you with this kind of problems in the future

5

Ok. I think I understand now. Here’s my final code which looks a lot like the solution.


function largestOfFour(arr) {
  // You can do this!
  
  let newArr = [];

  for (let i = 0; i < arr.length; i++) {
    let maxNumber = arr[i][0];

    for (let x = 1; x < arr[i].length; x++){
      
      if(arr[i][x] > maxNumber) {
        maxNumber = arr[i][x];
        

        console.log(newArr);
      }

    } newArr.push(maxNumber);
    console.log(newArr);

  }

  return newArr;
}

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

And I wanted to answer this:

Yeah, it did fail with negative numbers, that’s why instead of let maxNumber = 0;, it had to be the 1st value in the inner array like so: let maxNumber = arr[i][0];. And this variable had to be between the for loops so that maxNumber resets to the 0 index of the array every iteration.

I also had some difficulty understanding why the inner for loop in the solution had to start at 1. But now I understand that it is because my maxNumber is now already the 0th index of that array, the 2nd for loop should be 1.

Just took me about 4 hours to understand this challenge. And I love it. :smiley:

1 Like
6

Yeah, I think that was also in the javascript basics challenges. Thanks for reminding me! :smiley:

1 Like