题意

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.

给定一个数组及一个目标值，找出三个数，使它们的和与目标值的差值最小，输出它们的和。

解法

与上一题一样，遍历第一个数，然后用双指针算法遍历剩下两个数，随时比较它们与目标值的差值。

class Solution {public:    int threeSumClosest(vector
    
     & nums, int target)    {        sort(nums.begin(),nums.end());        int diff = 0x7fffffff;        int ans = 0;        for(int i = 0;i < nums.size();i ++)        {            int j = i + 1;            int k = nums.size() - 1;            while(j < k)            {                int sum = nums[i] + nums[j] + nums[k];                if(abs(sum - target) < diff)                {                    diff = abs(sum - target);                    ans = sum;                }                if(sum < target)                    j ++;                else                    k --;            }        }        return  ans;    }};