189. Rotate Array
阿新 • • 發佈:2017-08-04
int eas word ase post class efault diff tab
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. [show hint] Related problem: Reverse Wordsin a String II
三步翻轉法, 同 Recover Rotated Sorted Array , 註意反轉順序和k範圍.
如果:
reverse(nums, 0, k);
reverse(nums, k + 1, len-1);
reverse(nums, 0, len-1);
則:
Input:[1,2] 0 Output:[2,1] Expected:[1,2] 而先整體反轉則有效控制此情況的發生public void rotate(int[] nums, int k) { int len = nums.length; k %= len; reverse(nums, 0, len-1); reverse(nums, 0, k-1); reverse(nums, k, len-1); } public void reverse(int[] nums, int l, int r) { while (l <= r) { int temp = nums[l]; nums[l] = nums[r]; nums[r] = temp; l++; r--; } }
189. Rotate Array