#189. Rotate Array

• Solved

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

My Solution

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public class Solution {
    public void Rotate(int[] nums, int k) {
        int n = nums.Length;
        int[] rotated = new int[n];

        for (int i = 0; i < n; i++) {
            rotated[(i + k) % n] = nums[i];
        }

        for (int i = 0; i < n; i++) {
            nums[i] = rotated[i];
        }        
    }
}

Runtime

0 ms / Beats 100.00%

Memory

62.58 MB / Beats 87.19%

Big O Notation

Time complexity: O(n)
Space complexity: O(n)

Best Solution

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public class Solution {
    public void Rotate(int[] nums, int k) {
        k = k % nums.Length;
        if (k != 0) {
            int[] temp = new int[nums.Length];
            Array.Copy(nums, nums.Length - k, temp, 0, k);
            Array.Copy(nums, 0, temp, k, nums.Length - k);
            Array.Copy(temp, 0, nums, 0, nums.Length);
        }       
    }
}

Runtime

0 ms / Beats 100.00%

Memory

62.6 MB / Beats 85.85%

Big O Notation

Time complexity: O(n)
Space complexity: O(n)