Recover Rotated Sorted Array

Given a rotated sorted array, recover it to sorted array in-place.

Clarification

What is rotated array?

• For example, the orginal array is [1,2,3,4], The rotated array of it can be [1,2,3,4], [2,3,4,1], [3,4,1,2], [4,1,2,3]

Example

[4, 5, 1, 2, 3] -> [1, 2, 3, 4, 5]

分析：

利用公式 (A^TB^T)^T = BA

public class Solution {

    public void recoverRotatedSortedArray(ArrayList<Integer> nums) {
        if (nums == null || nums.size() == 0 || nums.size() == 1) return;
        int i = 0;
        for (; i < nums.size() - 1; i++) {
            if (nums.get(i) > nums.get(i + 1))
                break;
        }
        if (i == nums.size() - 1) return;
        reverse(nums, 0, i);
        reverse(nums, i + 1, nums.size() - 1);
        reverse(nums, 0, nums.size() - 1);
    }

    public void reverse(ArrayList<Integer> nums, int l, int r) {
        while (l < r) {
            int temp = nums.get(l);
            nums.set(l, nums.get(r));
            nums.set(r, temp);
            l++;
            r--;
        }
    }
}