分析

难度 易

来源

题目

Given an array, rotate the array to the right by k steps, where k is non-negative.

Example 1:

Input: [1,2,3,4,5,6,7] and k = 3

Output: [5,6,7,1,2,3,4]

Explanation:

rotate 1 steps to the right: [7,1,2,3,4,5,6]

rotate 2 steps to the right: [6,7,1,2,3,4,5]

rotate 3 steps to the right: [5,6,7,1,2,3,4]

Example 2:

Input: [-1,-100,3,99] and k = 2

Output: [3,99,-1,-100]

Explanation:

rotate 1 steps to the right: [99,-1,-100,3]

rotate 2 steps to the right: [3,99,-1,-100]

Note:

• Try to come up as many solutions as you can, there are at least 3 different ways to solve this problem.
• Could you do it in-place with O(1) extra space?

解答

Runtime: 1 ms, faster than 52.53% of Java online submissions for Rotate Array.

1 package LeetCode; 2  3 public class L189_RotateArray { 4     // Reverse the first n - k elements, 5     // the last k elements, and then all the n elements. 6     public void rotate(int[] nums, int k) { 7         int len=nums.length; 8         k=k%len; 9         int temp=0;10         for(int i=0;i<(len-k)/2;i++){11             temp=nums[i];12             nums[i]=nums[len-k-1-i];13             nums[len-k-1-i]=temp;14         }15         for(int i=0;i