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/**

* 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.

*

* Hint:

* Could you do it in-place with O(1) extra space?

* Related problem: Reverse Words in a String II

*

*/

public class RotateArray189 {

public void rotate(int[] nums, int k) {

int kk = k % nums.length;

if (kk == 0) return;

boolean[] visited = new boolean[nums.length];

for (int i=0; i<nums.length; i++) {

if (visited[i]) continue;

int j = i;

int r = nums[j];

while (true) {

int nextIndex = (j+k) % nums.length;

int temp = nums[nextIndex];

nums[nextIndex] = r;

visited[nextIndex] = true;

r = temp;

j = nextIndex;

if (j == i) break;

}

}

}

/**

* https://leetcode.com/problems/rotate-array/solution/

*/

public void rotate2(int[] nums, int k) {

int[] a = new int[nums.length];

for (int i = 0; i < nums.length; i++) {

a[(i + k) % nums.length] = nums[i];

}

for (int i = 0; i < nums.length; i++) {

nums[i] = a[i];

}

}

/**

* https://leetcode.com/problems/rotate-array/solution/

*/

public void rotate3(int[] nums, int k) {

k = k % nums.length;

int count = 0;

for (int start = 0; count < nums.length; start++) {

int current = start;

int prev = nums[start];

do {

int next = (current + k) % nums.length;

int temp = nums[next];

nums[next] = prev;

prev = temp;

current = next;

count++;

} while (start != current);

}

}

/**

* https://leetcode.com/problems/rotate-array/solution/

*/

public void rotate4(int[] nums, int k) {

k %= nums.length;

reverse(nums, 0, nums.length - 1);

reverse(nums, 0, k - 1);

reverse(nums, k, nums.length - 1);

}

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 rotate5(int[] nums, int k) {

if (nums == null || nums.length <= 1) return;

int len = nums.length;

k = k % len;

if (k == 0) return;

int count = 0;

for (int i=0; i<k && count < len; i++) {

count += cipher(nums, k, i, len);

}

}

private int cipher(int[] nums, int k, int start, int len) {

int res = 0;

int i = start;

int pre = nums[i];

do {

i = (i + k) % len;

int old = nums[i];

nums[i] = pre;

pre = old;

res++;

} while (i != start);

return res;

}

}