016 3Sum Closest

最新推荐文章于 2020-06-22 19:16:05 发布

walter1990

最新推荐文章于 2020-06-22 19:16:05 发布

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分类专栏： Leetcode

本文链接：https://blog.youkuaiyun.com/suichen1/article/details/51058327

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本文介绍了一种算法，用于在给定的整数数组中找到三个数的和，该和与指定的目标数最为接近。通过排序和双指针技巧，实现高效求解。

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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).

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#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
using namespace std;

class Solution {
public:
	int threeSumClosest(vector<int>& nums, int target) {
		int len = nums.size(), diff = 0, flag=0, ans = 0;

		sort(nums.begin(), nums.end());

		for(int i=0; i < len; i++) {
			for(int l=i+1, r=len-1; l < r;) {
				int tmp = nums[i]+nums[l]+nums[r];
				if(flag == 0) {
					flag = 1;
					diff = abs(tmp-target);
					ans = tmp;
				} else {
					if(abs(tmp-target) < diff) {
						ans = tmp;
						diff = abs(tmp-target);
					}
				}
				if(tmp > target) {
					r--;
				} else if(tmp < target) {
					l++;
				} else {
					return target;
				}
			}
		}

		return ans;
	}
};