sock_merchant.py: Matching socks by color (#5761)

* Python file for finding number of pairs

* updating DIRECTORY.md

* fixed iterative_pair.py

* further fixed with type casting

* fixed naming conventions

* further fixed with naming convention

* documented done

* build issue fixed

* updating DIRECTORY.md

* Revert "documented done"

This reverts commit 3be15ca374.

* Update canny.py

* Update test_digital_image_processing.py

* Update sobel_filter.py

* requirements.txt fixed

* keras<2.7.0

* Update sock_merchant.py

* doctest with black fixed

* Update sock_merchant.py

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: Christian Clauss <cclauss@me.com>

maths/sock_merchant.py

@@ -0,0 +1,20 @@
+from collections import Counter
+
+
+def sock_merchant(colors: list[int]) -> int:
+    """
+    >>> sock_merchant([10, 20, 20, 10, 10, 30, 50, 10, 20])
+    3
+    >>> sock_merchant([1, 1, 3, 3])
+    2
+    """
+    return sum(socks_by_color // 2 for socks_by_color in Counter(colors).values())
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()
+
+    colors = [int(x) for x in input("Enter socks by color :").rstrip().split()]
+    print(f"sock_merchant({colors}) = {sock_merchant(colors)}")