Added strand sort

sorts/strand_sort.py

@@ -0,0 +1,60 @@
+from functools import partial
+import operator
+
+
+def strand_sort(arr: list, solution: list, _operator: callable):
+ """
+ Strand sort implementation
+ source: https://en.wikipedia.org/wiki/Strand_sort
+
+ :param arr: Unordered input list
+ :param solution: Ordered output list
+ :param _operator: Operator lt/gt to specify ascent/descent version
+
+ Examples:
+ >>> solution_1 = []
+ >>> strand_sort([4, 2, 5, 3, 0, 1], solution_1, operator.gt)
+ >>> solution_1
+ [0, 1, 2, 3, 4, 5]
+
+ >>> solution_2 = []
+ >>> strand_sort([4, 2, 5, 3, 0, 1], solution_2, operator.lt)
+ >>> solution_2
+ [5, 4, 3, 2, 1, 0]
+ """
+ if not arr:
+ return
+
+ sublist = [arr.pop(0)]
+ for i, item in enumerate(arr):
+ if _operator(item, sublist[-1]):
+ sublist.append(item)
+ arr.pop(i)
+
+ # merging sublist into solution list
+ if not solution:
+ solution.extend(sublist)
+ else:
+ while sublist:
+ item = sublist.pop(0)
+ for i, xx in enumerate(solution):
+ if not _operator(item, xx):
+ solution.insert(i, item)
+ break
+ else:
+ solution.append(item)
+
+ strand_sort(arr, solution, _operator)
+
+
+strand_asc = partial(strand_sort, _operator=operator.gt)
+strand_desc = partial(strand_sort, _operator=operator.lt)
+
+if __name__ == "__main__":
+ solution = []
+ strand_asc([4, 3, 5, 1, 2], solution)
+ assert solution == [1, 2, 3, 4, 5]
+
+ solution = []
+ strand_desc([4, 3, 5, 1, 2], solution)
+ assert solution == [5, 4, 3, 2, 1]