【Leetcode】之3Sum Closest

一.问题描述

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).

二.我的解题思路

这道题和上一道题几乎完全一样，这道题还更简单一些，因为只需要返回sum值而不需要返回具体的三个数。沿用上一题的排序+双指针的思路，测试通过的程序如下：

class Solution {public:    int threeSumClosest(vector<int>& nums, int target) {        sort(nums.begin(),nums.end());        int len=nums.size();        int tmp_min=100000;        int res;        for(int i=0;i<len;i++)        {            if(i>0&&nums[i]==nums[i-1])                continue;            int st=i+1;int end=len-1;            while(st<end)            {                int curr_value=nums[i]+nums[st]+nums[end];                int curr_dist=abs(curr_value-target);                if(curr_dist<tmp_min)                {                    tmp_min=curr_dist;                    res=curr_value;                }                if(curr_value>target)                    end--;                if(curr_value<target)                    st++;                if(curr_value==target)                    return target;            }        }        return res;     }};