LeetCode-in-All
189. Rotate Array
Medium
Given an array, 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 - 10 <= 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
func reverse(nums []int, l, r int) {
for l <= r {
nums[l], nums[r] = nums[r], nums[l]
l++
r--
}
}
func rotate(nums []int, k int) {
n := len(nums)
t := n - (k % n)
reverse(nums, 0, t-1)
reverse(nums, t, n-1)
reverse(nums, 0, n-1)
}