HELP - Return largest number in array problem

HELP - Return largest number in array problem
0

#1

Anybody know why this doesn’t pass the test? It returns the wanted output every time.

var storearr = [];

function largestOfFour(arr) {
  for (var i = 0; i < arr.length; i++) {
    var digitarr = arr[i].sort(function(a,b) {
      return b-a;
    });
    storearr.push(digitarr[0]);
  }
  return storearr;
}

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

#2

The global storearr is being reused for all test cases without being reinitialized - best to avoid global variables - turn it into a local variable of the function - you can see what’s going wrong with console.log


Return largest number array challenge!
#3

Thank you! Solved! :slight_smile:


#4

I made this really simple in JavaScript.

function max(arr){
  var max = arr[0];
  for(var i = 1; i < arr.length; i++){
    if(arr[i] > max){
      max = arr[i];
    }
  }
  return max;
}

It’s all about efficiency and minimal code.


#5

By the way, a little trick:

See how there’s Math.max() ? Well, it takes a variadic number of arguments, so for example

Math.max(1, 2) // 2
Math.max(3, -5, 1) // 3

Are totally valid but you can’t pass an array to it. What you could do is:

// a) Use apply syntax, compatible with all browsers
Math.max.apply(null, [1, 2, 3]) // 3

// b) Use the ES6 spread operator
Math.max(...[1, 2, 3]) // 3

So my solution is

const largestNums = xss => xss.map(xs => Math.max(...xs))

#6

@geekysmurf - Your solution does not correctly solve the challenge. Your solution returns the largest number of a single array, but does not return an array of the largest number in each sub-array.


#7

function largestOfFour(arr) {
// You can do this!
var a = 0, max = 0, b = [];
while( a < arr.length){
for(var i = 0; i < arr[a].length; i++){
if(arr[a][i] > max){
max = arr[a][i];
}
}
b[a] = max;
max = 0;
a++;
}
return b;
}
Hope this code does find max in each sub-array and put each maximum number in a new array which is returned at last.


#8

Wow! That’s one tidy solution! :slight_smile:


#9

This is indeed a very neat solution, but sadly ES6 is not available in the FCC interpreter (afaict) so you’d need to use a regular function and ‘apply’ to pass the tests.

function largestOfFour(arr) {
    return arr.map(function(xs){
        return Math.max.apply(Math, xs);
  });
}