Today I'm sharing a simple solution to the largest number problem on Leetcode.

The problem statement asks us to sort a given list of positive integers such that it forms the largest possible number, returning it as a string.

In the examples provided, we see that with the input `[10,2]`

the expected output is `"210"`

and with `[3,30,34,5,9]`

it's `"9534330"`

.

At first glance, I thought that the default dictionary `sort()`

we get for "free" in JS and the Array `reverse()`

method would do the trick because of the implicit type coercion that often surprises people. See, if we have an array `nums = [10, 2]`

, then `nums.sort()`

will output `[ 10, 2]`

because Javascript compares "10" to "2" as strings, not as numbers. This means that `nums.sort().reverse().join('')`

outputs `"210"`

which is in fact the ~~droid~~ largest number we are looking for.

There's a catch though, the largest number possible from an array of integers isn't the same as the array lexicographically sorted in descending order. For instance, `nums = [3, 10, 2, 1, 100]`

once sorted, reversed and formatted into a string returns `"32100101"`

but the highest possible number is `"32110100"`

!

Here's what I came up with:

```
var largestNumber = function(nums) {
if (Math.max(...nums) == 0) return '0';
const res = nums.map(String).sort((a, b) => {
if (a.length !== b.length) {
const aStr = a + b;
const bStr = b + a;
return bStr - aStr;
}
return b - a;
}).join('');
return res;
};
```

//Runtime: 60 ms, faster than 91.89%

//Memory Usage: 35.3 MB, less than 100.00%

## Discussion