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]

public int arrayPairSum(int[] nums) {
        if(nums == null || nums.length == 0){
            return 0;
        }
        Arrays.sort(nums);
        int sum = 0;
        for(int i = 0; 2 * i < nums.length; i++){
            sum += nums[i * 2];
        }
        return sum;
    }