leetcode解题: Array Partition I (561)

发表于 | 分类于

Given an array of 2n integers, your task is to group these integers into n pairs of integer, say (a1, b1), (a2, b2), …, (an, bn) which makes sum of min(ai, bi) for all i from 1 to n as large as possible.

Example 1:

1
2
3
4
Input: [1,4,3,2]
Output: 4
Explanation: n is 2, and the maximum sum of pairs is 4.

Note:
n is a positive integer, which is in the range of [1, 10000].
All the integers in the array will be in the range of [-10000, 10000].

解法1：

这题其实是一个数学题，先排序之后每两个组成一组的话选出的最小值的和是最大的。
Java

1
2
3
4
5
6
7
8
9
10
11
12
public class Solution {
    public int arrayPairSum(int[] nums) {
        Arrays.sort(nums);
        
        int sum = 0;
        for (int i = 0; i <nums.length; i = i + 2) {
            sum += nums[i];
        }
        
        return sum;
    }
}