[LeetCode&Python] Problem 561. Array Partition I

Posted 2021-01-07 chiyeung

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].

 

My method:

Step 1: sort the list L

Step 2: sum(L[0]+L[2]+L[4]+...+L[2n-2])

 

Code:

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