LeetCode-in-Ruby.github.io
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
# @param {Integer[]} nums
# @param {Integer} k
# @return {Void} Do not return anything, modify nums in-place instead.
def rotate(nums, k)
n = nums.length
t = n - (k % n)
reverse_rotate(nums, 0, t - 1)
reverse_rotate(nums, t, n - 1)
reverse_rotate(nums, 0, n - 1)
end
def reverse_rotate(nums, l, r)
while l <= r
temp = nums[l]
nums[l] = nums[r]
nums[r] = temp
l += 1
r -= 1
end
end