Find the array with the largest number in a 2d array with Javascript

Question

This is my attempt and it works fine, but I need to return the array containing the largest number, not the largest number itself.

Also, I want to know if there is a way to use deep-equal to compare inner arrays in 2D arrays.

function largestOfFour(arr) {
	for (var i = 0; i < arr.length; i++) {
		var largest = [0][0];
		for (var j = 0; j < arr[i].length; j++) {
			if (arr[i][j] > largest) {
				largest = arr[i][j];
			}
		}
	}

	return largest;

}

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

console.log(largest);

possible duplicate of stackoverflow.com/questions/1669190/… — durbnpoisn
– durbnpoisn, Commented Sep 16, 2015 at 19:19
@durbnpoisn this is asking how to find the array with the largest number in a 2D array with Javascript, not the largest number of a (1D) array. — James Ray
– James Ray, Commented Mar 4, 2019 at 9:53

dandavis · Accepted Answer · 2015-09-16 19:36:33Z

1

just for fun using new array methods:

  function largestOfFour(r){
    var biggest=Math.max.apply(null, r.join(",").split(",")); //merge arrays then find largest number in flat
    return  r.find( /./.test, RegExp("\\b"+biggest+"\\b") ); // find by matching element of sub-array to biggest flat array value
  }


  var largest=largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]);
  alert(largest); // shows "1000, 1001, 857, 1"

answered Sep 16, 2015 at 19:36

dandavis

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2 Comments

dev_sahar Over a year ago

thanks for your answer, but I guess that is a little complex for me. I am still learning JavaScript so loops are the easiest way for me at least for now.

James Ray Over a year ago

Additionally, as per stackoverflow.com/a/54980012/7438857, using a loop is actually more performant.

gvgvgvijayan · Accepted Answer · 2020-12-17 18:32:54Z

1

Easy way to find largest numbers in 2D array

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

Function explanation:

Array's map method will iterate and execute the callback on each item and populate the array with the computed value
Math's max method will get the biggest value in the given set of values
Once the max value computed it will be pushed to the array arr

edited Dec 17, 2020 at 18:32

gvgvgvijayan

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answered Aug 9, 2019 at 12:53

Zhivko Zhelev

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2 Comments

Wang Liang Over a year ago

add more description

Zhivko Zhelev Over a year ago

Easy way to find largest numbers in 2D array.

Jeff Noel · Accepted Answer · 2015-09-16 19:25:40Z

0

Create another variable and store the arr[i] array at the same time that you note the biggest number. You could remove largest variable if you only need the largest array (or replace largestOrigin by it).

JavaScript

function largestOfFour(arr) {
    var largest = 0,
        largestOrigin = [];

    for(var i = 0; i < arr.length; i++){ 
        for (var j = 0; j < arr[i].length; j++) {
            if(arr[i][j] > largest){
                largest = arr[i][j];
                largestOrigin = arr[i];
            }
        }
    }
    return largestOrigin;
}

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

JSFiddle (live demo)

answered Sep 16, 2015 at 19:25

Jeff Noel

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Comments

TylerMayfield · Accepted Answer · 2016-09-06 16:56:11Z

0

I'm also working on those freecodecamp bonfires :). Here was my solution:

function largestOfFour(arr) {
 var max = [];
   for(var i = 0; i < arr.length; i++){
     max.push(Math.max.apply(Math, arr[i]));
  }

  return max;
}

answered Sep 6, 2016 at 16:56

TylerMayfield

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