In Simple Words: In-place 3-step reversal trick: 1. Reverse the entire array. 2. Reverse the first $k$ elements. 3. Reverse the remaining $N - k$ elements. - Time: $O(N)$ | Space: $O(1)$ Python 3 python def rotate(nums: list[int]...

Q15: Rotate Array. - DSA Patterns (Multi-Lang)

In Simple Words: In-place 3-step reversal trick:

Reverse the entire array.
Reverse the first $k$ elements.
Reverse the remaining $N - k$ elements.

Time: $O(N)$ | Space: $O(1)$

Multi-Language SolutionsPython 3 • JavaScript • TypeScript • Java • C++

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def rotate(nums: list[int], k: int) -> None:
    k = k % len(nums)
    def reverse(l, r):
        while l < r:
            nums[l], nums[r] = nums[r], nums[l]
            l += 1; r -= 1
    
    reverse(0, len(nums) - 1)
    reverse(0, k - 1)
    reverse(k, len(nums) - 1)