Description
Given an integer array nums
, rotate the array to the right by k
steps, where k
is non-negative.
Example 1:
Input: nums = [1,2,3,4,5,6,7], 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: nums = [-1,-100,3,99], 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]
Constraints:
1 <= nums.length <= 105
-231 <= nums[i] <= 231 - 1
0 <= k <= 105
Follow up:
- Try to come up with as many solutions as you can. There are at least three different ways to solve this problem.
- Could you do it in-place with
O(1)
extra space?
Solution
Python3
class Solution:
def rotate(self, nums: List[int], k: int) -> None:
n = len(nums)
k %= n
def reverseL(start, end):
while start < end:
nums[start], nums[end] = nums[end], nums[start]
start += 1
end -= 1
reverseL(0, n - 1)
reverseL(0, k - 1)
reverseL(k, n - 1)
C++
class Solution {
public:
void rotate(vector<int>& nums, int k) {
int n = nums.size();
k %= n;
reverse(nums.begin(), nums.end());
reverse(nums.begin(), nums.begin()+k);
reverse(nums.begin()+k, nums.end());
}
};