数据结构与算法：leetcode_561_ Array Partition I

• Description
  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
  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).
  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].
• Solution

    public int arrayPairSum(int[] nums) {
        int sum = 0;
        for (int i = 0; i < nums.length; i++) {
            for (int j = nums.length - 1; j > i; j--) {
                if (nums[i] > nums[j]) {
                    int temp = nums[i];
                    nums[i] = nums[j];
                    nums[j] = temp;
                }
            }
        }
        for (int k = 0; k < nums.length - 1;) {
            sum += nums[k];
            k += 2;
        }
        System.out.println(sum);
        return sum;
    }