Problem
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.
Note:
- 3 <= A.length <= 10000
- 1 <= A[i] <= 10^6
Example1
Input: [2,1,2]
Output: 5
Example2
Input: [1,2,1]
Output: 0
Example3
Input: [3,2,3,4]
Output: 10
Example4
Input: [3,6,2,3]
Output: 8
Solution
class Solution {
public:
int largestPerimeter(vector<int>& A) {
sort(A.begin(),A.end());
for(int i = A.size()-1;i>=2;--i)
{
if(A[i-2] + A[i-1] > A[i])
return A[i] + A[i-1] + A[i-2];
}
return 0;
}
};