3Sum Closest
Desicription
Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution.
代码语言：javascript复制For example, given array S = {-1 2 1 -4}, and target = 1.
The sum that is closest to the target is 2. (-1 2 1 = 2).Solution
代码语言：javascript复制class Solution {
public:
int threeSumClosest(vector<int>& nums, int target) {
if(nums.size() == 3)
return nums[0] nums[1] nums[2];
std::sort(nums.begin(), nums.end());
int ans = nums[0] nums[1] nums[2];
for(int i = 0; i < nums.size() - 2; i ){
int left = i 1;
int right = nums.size()-1;
while(left < right){
int sum = nums[i] nums[left] nums[right];
if(abs(target - sum) < abs(target - ans))
ans = sum;
if(ans == target)
return ans;
if(sum > target)
right--;
else
left ;
}
}
return ans;
}
};
