Add Patience Sort

DIRECTORY.md

@@ -712,6 +712,7 @@
   * [Odd Even Transposition Parallel](https://github.com/TheAlgorithms/Python/blob/master/sorts/odd_even_transposition_parallel.py)
   * [Odd Even Transposition Single Threaded](https://github.com/TheAlgorithms/Python/blob/master/sorts/odd_even_transposition_single_threaded.py)
   * [Pancake Sort](https://github.com/TheAlgorithms/Python/blob/master/sorts/pancake_sort.py)
+  * [Patience Sort](https://github.com/TheAlgorithms/Python/blob/master/sorts/patience_sort.py)
   * [Pigeon Sort](https://github.com/TheAlgorithms/Python/blob/master/sorts/pigeon_sort.py)
   * [Pigeonhole Sort](https://github.com/TheAlgorithms/Python/blob/master/sorts/pigeonhole_sort.py)
   * [Quick Sort](https://github.com/TheAlgorithms/Python/blob/master/sorts/quick_sort.py)

sorts/patience_sort.py

@@ -0,0 +1,64 @@
+from bisect import bisect_left
+from functools import total_ordering
+from heapq import merge
+
+"""
+A pure Python implementation of the patience sort algorithm
+
+For more information: https://en.wikipedia.org/wiki/Patience_sorting
+
+This algorithm is based on the card game patience
+
+For doctests run following command:
+python3 -m doctest -v patience_sort.py
+
+For manual testing run:
+python3 patience_sort.py
+"""
+
+
+@total_ordering
+class Stack(list):
+    def __lt__(self, other):
+        return self[-1] < other[-1]
+
+    def __eq__(self, other):
+        return self[-1] == other[-1]
+
+
+def patience_sort(collection: list) -> list:
+    """A pure implementation of quick sort algorithm in Python
+
+    :param collection: some mutable ordered collection with heterogeneous
+    comparable items inside
+    :return: the same collection ordered by ascending
+
+    Examples:
+    >>> patience_sort([1, 9, 5, 21, 17, 6])
+    [1, 5, 6, 9, 17, 21]
+
+    >>> patience_sort([])
+    []
+
+    >>> patience_sort([-3, -17, -48])
+    [-48, -17, -3]
+    """
+    stacks = []
+    # sort into stacks
+    for element in collection:
+        new_stacks = Stack([element])
+        i = bisect_left(stacks, new_stacks)
+        if i != len(stacks):
+            stacks[i].append(element)
+        else:
+            stacks.append(new_stacks)
+
+    # use a heap-based merge to merge stack efficiently
+    collection[:] = merge(*[reversed(stack) for stack in stacks])
+    return collection
+
+
+if __name__ == "__main__":
+    user_input = input("Enter numbers separated by a comma:\n").strip()
+    unsorted = [int(item) for item in user_input.split(",")]
+    print(patience_sort(unsorted))