(Easy) Largest Perimeter Triangle LeetCode

Given an array A of positive lengths, return the largest perimeter of a triangle with non-zero area, formed from 3 of these lengths.

If it is impossible to form any triangle of non-zero area, return 0.

Example 1:

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

Example 2:

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

Example 3:

Input: [3,2,3,4]
Output: 10

Example 4:

Input: [3,6,2,3]
Output: 8

Note:

1. 3 <= A.length <= 10000
2. 1 <= A[i] <= 10^6

扫描二维码关注公众号，回复： 6925348 查看本文章

class Solution {
    public int largestPerimeter(int[] A) {
        
        if (A.length <3){
            return 0;
        }
      
        Arrays.sort(A);
        
        int len = A.length;
        for(int i = len -3; i>=0;i--){
            
            if(calc(A[i],A[i+1],A[i+2])){
                
                return A[i]+A[i+1]+A[i+2];
            }
        }
        return 0;
    }
    
    public boolean calc(int a, int b , int c){
        if(a+b> c && a+c > b && b+c > a){
            return true;
        }
        else {
            return false;
        }
    }
}