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.
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).
给定一个数组，从中找出三个数，使得三个数的和与目标值最接近。返回三个数的和
class Solution {
public:
int threeSumClosest(vector<int> &num, int target) {
int result=0;
int size=num.size();
if(size<3)return result;
int minDiff=INT_MAX;
int targetSum=0;
sort(num.begin(), num.end()); //排序
for(int p1=0; p1<size-2; p1++){
if(p1!=0 && num[p1]==num[p1-1])continue; //第一个数排重
int p2=p1+1;
int p3=size-1;
while(p2<p3){
if(p2!=p1+1 && num[p2]==num[p2-1]){p2++;continue;} //第二个数排重
int sum=num[p1]+num[p2]+num[p3];
if((int)abs(sum-target)<minDiff){minDiff=(int)abs(sum-target); targetSum=sum;}
if(sum>target)p3--;
else if(sum<target)p2++;
else return targetSum;
}
}
return targetSum;
}
};LeetCode 016 3Sum Closest,布布扣,bubuko.com
原文：http://blog.csdn.net/harryhuang1990/article/details/25962903