Rotate an array of n elements to the right by k steps. For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4]. Note: Try to come up as many solutions as you can, there are at least 3 different ways to solve this problem
public class RotateArray { //申请一个新的数组 public void rotate2(int[] nums, int k) { int[] arr = new int[nums.length]; for(int i=0;i<nums.length;i++) { arr[(i+k)%nums.length] = nums[i]; } System.arraycopy(arr, 0, nums, 0, arr.length); } //空间复杂度O(1) public void rotate(int[] nums,int k) { if(nums==null || nums.length<2) { return; } //保证k在0-nums.length-1 k = k % nums.length; reverse(nums,0,nums.length-1-k);//翻转前部分 reverse(nums,nums.length-k,nums.length-1);//翻转后部分 reverse(nums,0,nums.length-1); //翻转整体 } private void reverse(int[] nums, int start, int end) { while(start<end) { int tmp = nums[start]; nums[start] = nums[end]; nums[end] = tmp; start++; end--; } }