public class DayCode {    public static void main(String[] args) {        int[] nums = new int[]{1,1,0,1,1,1};        Integer ans = new DayCode().arrayPairSum(nums);        System.out.println("ans is " + ans);    }
    /**     * https://leetcode-cn.com/problems/array-partition-i/     * @param nums     * @return     */    public int arrayPairSum(int[] nums) {        Arrays.sort(nums);        int ans = 0;        for (int i = 0; i < nums.length; i += 2) {            ans += nums[i];        }        return ans;    }}