976. Largest Perimeter Triangle

 Given an integer array nums, return the largest perimeter of a triangle with a non-zero area, formed from three of these lengths. If it is impossible to form any triangle of a non-zero area, return 0.

 

Example 1:

Input: nums = [2,1,2]
Output: 5

Example 2:

Input: nums = [1,2,1]
Output: 0

 

Constraints:

• 3 <= nums.length <= 104
• 1 <= nums[i] <= 106

Soluation:

In Javascript:

var largestPerimeter = function(nums) {
    nums.sort((a, b) => a - b);
    let i = nums.length - 1;
    while(i >= 0){
        if (nums[i] < nums[i-1] + nums[i-2]){
            return nums[i] + nums[i-1] + nums[i-2];
        } else {
              i--;
        }
    }
    return 0;
};