lintcode-----3sum smaller

题目描述：
Given an array of n integers nums and a target, find the number of index triplets i, j, k with 0 <= i < j < k < n that satisfy the condition nums[i] + nums[j] + nums[k] < target.

样例：
Given nums = [-2,0,1,3], target = 2, return 2.

Explanation:
Because there are two triplets which sums are less than 2:
[-2, 0, 1]
[-2, 0, 3]

思路直接三重循环并进行判断。

代码详解：

class Solution {
public:
    /**
     * @param nums:  an array of n integers
     * @param target: a target
     * @return: the number of index triplets satisfy the condition nums[i] + nums[j] + nums[k] < target
     */
    int threeSumSmaller(vector<int> &nums, int target) {
        // Write your code here
        int len=nums.size();
        int count=0;
        for(int i=0;i<len;i++){
            for(int j=i+1;j<len;j++){
                for(int k=j+1;k<len;k++){
                    if(nums[i]+nums[j]+nums[k]<target){
                        count++;
                    }
                }
            }
        }
        return count;

    }
};