1099. Two Sum Less Than K 小于 K 的两数之和

• 作者： 负雪明烛
• id： fuxuemingzhu
• 个人博客：http://fuxuemingzhu.cn/

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题目地址：https://leetcode-cn.com/problems/two-sum-less-than-k/

题目描述

Given an array A of integers and integer K, return the maximum S such that there exists i < j with A[i] + A[j] = S and S < K. If no i, j exist satisfying this equation, return -1.

Example 1:

Input: A = [34,23,1,24,75,33,54,8], K = 60
Output: 58
Explanation: 
We can use 34 and 24 to sum 58 which is less than 60.

Example 2:

Input: A = [10,20,30], K = 15
Output: -1
Explanation: 
In this case it's not possible to get a pair sum less that 15.

Note:

1. 1 <= A.length <= 100
2. 1 <= A[i] <= 1000
3. 1 <= K <= 2000

题目大意

给你一个整数数组 A 和一个整数 K，请在该数组中找出两个元素，使它们的和小于 K 但尽可能地接近 K，返回这两个元素的和。

如不存在这样的两个元素，请返回 -1。

解题方法

暴力求解

本来觉得这个题好难，但是看了数组的范围才有100个元素，果断暴力求解即可。

C++代码如下：

class Solution {
public:
    int twoSumLessThanK(vector<int>& A, int K) {
        const int N = A.size();
        int res = -1;
        int minDist = INT_MAX;
        for (int i = 0; i < N; i ++) {
            for (int j = i + 1; j < N; j ++) {
                int sum = A[i] + A[j];
                if (sum < K && K - sum < minDist) {
                    minDist = K - sum;
                    res = sum;
                }
            }
        }
        return res;
    }
};

日期

2019 年 9 月 18 日 —— 今日又是九一八