Given an array of integers, return indices of the two numbers such that they add up to a specific target.
You may assume that each input would have exactly one solution.
Example:
Given nums = [2, 7, 11, 15], target = 9,
Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].
解题思路
本题是3 sum的变种题，求三个数之和小于一个目标值的组数，和3 sum一样的思路，将3个数之和求出与目标值比较，如果小，结果加一。
代码如下：
class Solution{
public:
int threeSumSmaller(vector<int>& nums, int target) {
sort(nums.begin(), nums.end());
int res = 0;
int number = nums.size();
for(int i = 0; i < number - 2; ++i)
{
int l = i + 1 , r= number - 1;
while(l < r)
{
if(nums[i] + nums[l] + nums[r] < target)
{
res++;
l++;
} else{
r--;
}
}
}
return res;
}
};
