189. Rotate Array

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].

class Solution {
public:
	void rotate(vector<int>& nums, int k) {
		if (k <= 0) return;
		int len = nums.size();
		k = k%len;
		int i = 0, j = len - k - 1;
		while (i < j){
			swap(nums[i++], nums[j--]);
		}
		i = len - k, j = len - 1;
		while (i < j){
			swap(nums[i++], nums[j--]);
		}
		i = 0, j = len - 1;
		while (i < j){
			swap(nums[i++], nums[j--]);
		}
	}
};