[Leetcode] 3Sum Closest

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).

给定一个数组以及目标值，在数组中找三个数使得它们的和最接近目标值。

分析

这道题是 3Sum 的改进版，区别在于原来的题目找的是和为零的三个数，这道题找的是和最接近目标值的三个数，思路与原来题目一样，详情请看这里 。

代码

class Solution {
public:
int threeSumClosest(vector<int>& nums, int target) {
sort(nums.begin(), nums.end());
int sum = nums[0] + nums[1] + nums[2];
int diff = abs(sum - target);
for (int k = 0; k < nums.size(); k++) {
int i = k + 1, j = nums.size() - 1;
while (i < j) {
int tmp = nums[k] + nums[i] + nums[j];
if (diff > abs(tmp - target))
{sum = tmp; diff = abs(sum - target);}
if (tmp < target) i++;
else j--;
}
}
return sum;
}
};

相关问题

Two Sum

3Sum