Rotate Array

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Rotate array to the right by k steps using triple reverse

Rotate Array

Key Insight

Triple reverse: reverse all → reverse first k → reverse rest. Each reverse uses two pointers.

Step 1Setup
k=3, rotate right
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Rotate [1,2,3,4,5,6,7] right by k=3. Last 3 elements move to front.

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Learn the Pattern

Two PointersUse two pointers to traverse an array or string, reducing time complexity from O(n^2) to O(n) for problems involving pairs or subarrays.
Practice the Code

Step-by-Step Walkthrough: Rotate Array

Triple reverse: reverse all → reverse first k → reverse rest. Each reverse uses two pointers.

  1. Setup

    Rotate [1,2,3,4,5,6,7] right by k=3. Last 3 elements move to front.

  2. Reverse All

    Reverse entire array using two pointers converging.

  3. Reverse First k

    Reverse first k=3 elements to restore their order.

  4. Reverse Rest

    Reverse remaining elements from index k to end.

  5. Result

    Array rotated right by 3. Triple reverse achieves O(1) space.