Solution.java

package Array.No_561_Array_Partition_I;

import java.util.Arrays;

/**
 * FileName: Solution
 * Author:   mac
 * Date:     2019-02-21 10:07
 * Description: Array Partition I
 * <p>
 * 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.
 * <p>
 * Example 1:
 * Input: [1,4,3,2]
 * <p>
 * Output: 4
 * Explanation: n is 2, and the maximum sum of pairs is 4 = min(1, 2) + min(3, 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].
 */
public class Solution {
    public int arrayPairSum(int[] nums) {
        if (nums.length <= 1) return 0;
        Arrays.sort(nums);
        int resNum = 0;
        for (int i = 0; i < nums.length; i += 2)
            resNum += nums[i];
        return resNum;
    }
}