leetcode189

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

        public void Rotate(int[] nums, int k)
        {
            k %= nums.Length;
            reverse(nums, 0, nums.Length - 1);
            reverse(nums, 0, k - 1);
            reverse(nums, k, nums.Length - 1);
        }
}

https://leetcode.com/problems/rotate-array/#/description

 

 补充一个python的实现：

class Solution:
    def rotate(self, nums: 'List[int]', k: int) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        n = len(nums)#获取原数组的长度
        #将原数组用切片分两部分
        part1 = nums[n-k:]#右半部分，从第n-k个元素开始，到最后一个元素
        part2 = nums[:n-k]#右半部分，从第0个元素开始，到第n-k-1个元素
        nums.clear()#将原数组清空
        nums.extend(part1)#空数组先拼接右半数组
        nums.extend(part2)#空数组再拼接左半数组

 

Java版代码：

class Solution {
    public void reverse(int[] nums, int start, int end){
        while (start < end)
        {
            int temp = nums[start];
            nums[start] = nums[end];
            nums[end] = temp;
            start++;
            end--;
        }
    }
    public void rotate(int[] nums, int k) {
        k %= nums.length;
        reverse(nums, 0, nums.length - 1);
        reverse(nums, 0, k - 1);
        reverse(nums, k, nums.length - 1);
    }
}