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]
Hint:Could you do it in-place with O(1) extra space?
Related problem: Reverse Words in a String II
Solution1： 整体reverse + part reverse
类似: http://www.jianshu.com/p/5e74b3826441
思路：
Time Complexity: O(N) Space Complexity: O(1)
Solution2： With extra space Round1
思路：
Time Complexity: O(N) Space Complexity: O(N)
Solution1 Code：
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);
}
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--;
}
}
Solution2 Code：
class Solution {
public void rotate(int[] nums, int k) {
k = k % nums.length;
int[] tmp = new int[nums.length];
// copy nums'right part
int index = 0;
for(int i = nums.length - k; i < nums.length; i++) {
tmp[index++] = nums[i];
}
// copy nums'left part
for(int i = 0; i < nums.length - k; i++) {
tmp[index++] = nums[i];
}
// prepare the result
for(int i = 0; i < nums.length; i++) {
nums[i] = tmp[i];
}
}
}
