[leetcode]611. Valid Triangle Number

题目链接：https://leetcode.com/problems/valid-triangle-number/#/description

Given an array consists of non-negative integers, your task is to count the number of triplets chosen from the array that can make triangles if we take them as side lengths of a triangle.

Example 1:

Input: [2,2,3,4]Output: 3Explanation:Valid combinations are: 2,3,4 (using the first 2)2,3,4 (using the second 2)2,2,3

Note:

1. The length of the given array won't exceed 1000.
2. The integers in the given array are in the range of [0, 1000].

class Solution {public:    int triangleNumber(vector<int>& nums) {        int count=0;        if(nums.size()<3)            return count;        sort(nums.begin(),nums.end());        for(int i=0;i<nums.size()-2;i++)        {            int k=i+2;            for(int j=i+1;j<nums.size()-1 && nums[i]!=0;j++)            {                while(k<nums.size() && nums[i]+nums[j]>nums[k])                    k++;                count+=(k-j-1);            }        }        return count;    }};