LeetCode 977. 有序数组的平方

给定一个按非递减顺序排序的整数数组 A，返回每个数字的平方组成的新数组，要求也按非递减顺序排序。

示例 1：

输入：[-4,-1,0,3,10]
输出：[0,1,9,16,100]

示例 2：

输入：[-7,-3,2,3,11]
输出：[4,9,9,49,121]

提示：

1. 1 <= A.length <= 10000
2. -10000 <= A[i] <= 10000
3. A 已按非递减顺序排序。

 public int[] sortedSquares(int[] A) {
        int[] nums = new int[A.length];
        for (int i = 0; i < A.length; i++) {
            nums[i] = A[i] * A[i];
        }
        quickStart(0, A.length - 1, nums);
        return nums;
    }

    public static void quickStart(int left, int right, int[] nums) {
        if (left >= right) {
            return;
        }
        int dempLeft = left, dempRight = right;
        while (dempLeft != dempRight) {
            while (dempLeft < dempRight && nums[dempRight] >= nums[left]) {
                dempRight--;
            }
            while (dempLeft < dempRight && nums[dempLeft] <= nums[left]) {
                dempLeft++;
            }
            if (dempLeft != dempRight) {
                swap(nums, dempLeft, dempRight);
            }
        }
        if (left != dempLeft) {
            swap(nums, left, dempLeft);
        }
        quickStart(left, dempLeft - 1, nums);
        quickStart(dempRight + 1, right, nums);
    }

    private static void swap(int[] nums, int i, int j) {
        int num = nums[i];
        nums[i] = nums[j];
        nums[j] = num;
    }