Array Partition I

Question

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].

Tags

• Array

Thought

1. Sort the array of integers.
2. Sum all integers at the even indices in the sorted array.

Code

class Solution(object):
    def arrayPairSum(self, nums):
        """
        sort and get the sum of the subarray
        :type nums: List[int]
        :rtype: int
        """
        nums.sort()
        ans = 0
        for i in xrange(0, len(nums), 2):
            ans += nums[i]
        return ans