Rotate Array

189. Rotate Array

Difficulty: Easy

Related Topics: Array, Math, Two Pointer

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]

Code:

class Solution:
    def rotate(self, nums: List[int], k: int) -> None:
        first = 0
        last = len(nums)-1
        temp = 0
        for i in range(k):
            temp = nums[last]
            nums.insert(first, temp)
            nums.pop()
        return nums

Feedbacks:

I could solve this problem by just insert last element at index 0 and pop the list for k times. But it has O(n) time complexity which makes my code much slower than other algorithms used to solve this question. Also, I couldn’t find a way to implement two pointers which the question was really asking for.