[leetcode 189][轮转数组]

给定一个整数数组 nums，将数组中的元素向右轮转 k 个位置，其中 k 是非负数。

示例 1:
输入: nums = [1,2,3,4,5,6,7], k = 3
输出: [5,6,7,1,2,3,4]
解释:
向右轮转 1 步: [7,1,2,3,4,5,6]
向右轮转 2 步: [6,7,1,2,3,4,5]
向右轮转 3 步: [5,6,7,1,2,3,4]
示例 2:
输入：nums = [-1,-100,3,99], k = 2
输出：[3,99,-1,-100]
解释:
向右轮转 1 步: [99,-1,-100,3]
向右轮转 2 步: [3,99,-1,-100]

class Solution {
    public static void rotate(int[] nums, int k) {
        int n = nums.length;
        if (n <= 1) {
            return;
        }
        int index = k % n;
        reverse(nums, 0 , n - 1);
        reverse(nums, 0, index - 1);
        reverse(nums, index, n - 1);
    }

    public static void reverse(int[] nums, int start, int end) {
        while (end >= start) {
            int temp = nums[start];
            nums[start] = nums[end];
            nums[end] = temp;
            start++;
            end--;
        }
    }
}