probelms:

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). Solution；依然同3Sun一样 先排序再左右夹逼  不同的是再加入一个变量mingap用来记录最小值

class Solution {public:    int threeSumClosest(vector
     
      & nums, int target) {        int result=0;        int mingap=INT_MAX;  //无限宏                sort(nums.begin(),nums.end());                        for(auto a=nums.begin();a!=prev(nums.end(),2);a++)        {                        auto b=next(a);            auto c=prev(nums.end());                                    while(b