[CLOSED]LEET0561_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.

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].

"""

def arrayPairSum(L):
  L.sort()
  sum=0
  for i in range(int(len(L)/2)):
    sum+=L[2*i]
  return sum