Leetcode #561. Array Partition I

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:

Input: [1,4,3,2]

Output: 4
Explanation: n is 2, and the maximum sum of pairs is 4 = min(1, 2) + min(3, 4).

Note:

1.n is a positive integer, which is in the range of [1, 10000].

2.All the integers in the array will be in the range of [-10000, 10000]

题意：给出偶数倍数组，两两组成数字对，使得所有数字对中的最小的数字的和最大

想法：就是直接排个序，取奇数下标的数字即可，可以从后往前想，最大的肯定不能算在数字对中的最小，但是可以给它配一个第二大的使得第二个能生效，按照这样的递推想法最后我们就可以发现就是排序了取奇数下标的数字。

代码：

class Solution(object):
    def arrayPairSum(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        return sum(sorted(nums)[::2])