(C++)有效三角形的个数--双指针法

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