Sort Even and Odd Indices Independently

排序一个数组, 偶数index的数字递增, 奇数index的数字递减.

class Solution {
    public int[] sortEvenOdd(int[] nums) {
        int n = nums.length;
        List<Integer> odd = new ArrayList<>();
        List<Integer> even = new ArrayList<>();
        for(int i = 0; i < nums.length; i++){
            if(i % 2 == 0)
                even.add(nums[i]);
            else
                odd.add(nums[i]);
        }
        Collections.sort(even);
        Collections.sort(odd, Collections.reverseOrder());
        int[] res = new int[n]; 
        int j = 0;
        int k = 0;
        for(int i = 0; i < nums.length; i++){
            if(i % 2 == 0)
                res[i] = even.get(j++);
            else
                res[i] = odd.get(k++);
        }
        return res;
    }
}