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].

Note:

Try to come up as many solutions as you can, there are at least 3 different ways to solve this problem.

Related problem: Reverse Words in a String II

解答

三次翻转

第一次将整个数组反转，第二次将前k个元素翻转，第三次将剩下的元素翻转。

class Solution {
public:
void rotate(vector<int>& nums, int k) {
if(nums.empty())
return;
int n = nums.size();
if(k == n)
return;
if(k>n)
k = k%n;
reverse(nums.begin(),nums.end());
vector<int>::iterator rotatePoint = nums.begin()+k;
reverse(nums.begin(),rotatePoint);
reverse(rotatePoint,nums.end());

}
};