LeetCode: 189. Rotate Array
题目描述
Given an array, rotate the array to the right by k
steps, where k is non-negative.
Example 1:
Input: [1,2,3,4,5,6,7] and k = 3
Output: [5,6,7,1,2,3,4]
Explanation:
rotate 1 steps to the right: [7,1,2,3,4,5,6]
rotate 2 steps to the right: [6,7,1,2,3,4,5]
rotate 3 steps to the right: [5,6,7,1,2,3,4]
Example 2:
Input: [-1,-100,3,99] and k = 2
Output: [3,99,-1,-100]
Explanation:
rotate 1 steps to the right: [99,-1,-100,3]
rotate 2 steps to the right: [3,99,-1,-100]
Note:
- Try to come up as many solutions as you can, there are at least
3
different ways to solve this problem. - Could you do it in-place with
O(1)
extra space?
解题思路
递归求解,一次移动一位。
AC 代码
class Solution {
public:
void rotate(vector<int>& nums, int k) {
if(k == 0 || nums.empty()) return;
// 向右边移动一位
int lastNum = nums.back();
for(int i = nums.size()-1; i > 0; --i)
{
nums[i] = nums[i-1];
}
nums[0] = lastNum;
// 继续移动 k-1 位
rotate(nums, k-1);
}
};