From 788d95b4101389617ca9f7fd043998089f98df78 Mon Sep 17 00:00:00 2001
From: Anuska Roy <anuskaroy0410@gmail.com>
Date: Wed, 8 Oct 2025 17:41:28 +0530
Subject: [PATCH] added rotate_array.py (#13336)

* added rotate_array.py

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* fixed issues

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* fixed reverse issue

* added doctests

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* changed k to steps for a descriptive name

* fixed non-pep

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
---
 data_structures/arrays/rotate_array.py | 80 ++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)
 create mode 100644 data_structures/arrays/rotate_array.py

diff --git a/data_structures/arrays/rotate_array.py b/data_structures/arrays/rotate_array.py
new file mode 100644
index 000000000000..d5ce4b4078b3
--- /dev/null
+++ b/data_structures/arrays/rotate_array.py
@@ -0,0 +1,80 @@
+def rotate_array(arr: list[int], steps: int) -> list[int]:
+    """
+    Rotates a list to the right by steps positions.
+
+    Parameters:
+    arr (List[int]): The list of integers to rotate.
+    steps (int): Number of positions to rotate. Can be negative for left rotation.
+
+    Returns:
+    List[int]: Rotated list.
+
+    Examples:
+    >>> rotate_array([1, 2, 3, 4, 5], 2)
+    [4, 5, 1, 2, 3]
+    >>> rotate_array([1, 2, 3, 4, 5], -2)
+    [3, 4, 5, 1, 2]
+    >>> rotate_array([1, 2, 3, 4, 5], 7)
+    [4, 5, 1, 2, 3]
+    >>> rotate_array([], 3)
+    []
+    """
+
+    n = len(arr)
+    if n == 0:
+        return arr
+
+    steps = steps % n
+
+    if steps < 0:
+        steps += n
+
+    def reverse(start: int, end: int) -> None:
+        """
+        Reverses a portion of the list in place from index start to end.
+
+        Parameters:
+        start (int): Starting index of the portion to reverse.
+        end (int): Ending index of the portion to reverse.
+
+        Returns:
+        None
+
+        Examples:
+        >>> example = [1, 2, 3, 4, 5]
+        >>> def reverse_test(arr, start, end):
+        ...     while start < end:
+        ...         arr[start], arr[end] = arr[end], arr[start]
+        ...         start += 1
+        ...         end -= 1
+        >>> reverse_test(example, 0, 2)
+        >>> example
+        [3, 2, 1, 4, 5]
+        >>> reverse_test(example, 2, 4)
+        >>> example
+        [3, 2, 5, 4, 1]
+        """
+
+        while start < end:
+            arr[start], arr[end] = arr[end], arr[start]
+            start += 1
+            end -= 1
+
+    reverse(0, n - 1)
+    reverse(0, steps - 1)
+    reverse(steps, n - 1)
+
+    return arr
+
+
+if __name__ == "__main__":
+    examples = [
+        ([1, 2, 3, 4, 5], 2),
+        ([1, 2, 3, 4, 5], -2),
+        ([1, 2, 3, 4, 5], 7),
+        ([], 3),
+    ]
+
+    for arr, steps in examples:
+        rotated = rotate_array(arr.copy(), steps)
+        print(f"Rotate {arr} by {steps}: {rotated}")