# 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 <= 10^5
• -2^31 <= nums[i] <= 2^31 - 1
• 0 <= k <= 10^5

# Solution 1: Insert & Erase

## 效能

### Complexity

• Time Complexity: O(N^2), vector::erase takes O(N^2)
• Space Complexity: O(1)

### LeetCode Result

• Runtime: 32 ms
• Memory Usage: 25.8 MB

# Solution 2: std::reverse

## 效能

### Complexity

• Time Complexity: O(N), where vector::reverse takes O(N)
• Space Complexity: O(1)

### LeetCode Result

• Runtime: 33 ms
• Memory Usage: 24.9 MB

# Solution 3: std::rotate

## 思路

std::rotate 可以直接達成題目需要的功能。

## 效能

### Complexity

• Time Complexity: O(N)
• Space Complexity: O(1)

### LeetCode Result

• Runtime: 24 ms
• Memory Usage: 24.9 MB