【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;
}
};