add median of matrix (#9363)

* add median of matrix

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* update

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* fix formating

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---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Christian Clauss <cclauss@me.com>

Author: 3 people

matrix/median_matrix.py

@@ -0,0 +1,38 @@
+"""
+https://en.wikipedia.org/wiki/Median
+"""
+
+
+def median(matrix: list[list[int]]) -> int:
+    """
+    Calculate the median of a sorted matrix.
+
+    Args:
+        matrix: A 2D matrix of integers.
+
+    Returns:
+        The median value of the matrix.
+
+    Examples:
+        >>> matrix = [[1, 3, 5], [2, 6, 9], [3, 6, 9]]
+        >>> median(matrix)
+        5
+
+        >>> matrix = [[1, 2, 3], [4, 5, 6]]
+        >>> median(matrix)
+        3
+    """
+    # Flatten the matrix into a sorted 1D list
+    linear = sorted(num for row in matrix for num in row)
+
+    # Calculate the middle index
+    mid = (len(linear) - 1) // 2
+
+    # Return the median
+    return linear[mid]
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()