From 4d1b075086cf59c10c8d8c5fdf7cea133818203a Mon Sep 17 00:00:00 2001
From: Stefan Harmuth <pennywise@drock.de>
Date: Mon, 25 Dec 2023 11:24:12 +0100
Subject: [PATCH] NEW: itertools.len_permutations() and
 itertools.len_combinations() -> get the amount of results the respective
 itertools function would yield

---
 src/tools/itertools.py | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 src/tools/itertools.py

diff --git a/src/tools/itertools.py b/src/tools/itertools.py
new file mode 100644
index 0000000..8e36214
--- /dev/null
+++ b/src/tools/itertools.py
@@ -0,0 +1,20 @@
+from math import factorial
+from typing import Sized
+
+
+def len_combinations(iterable: Sized, r: int) -> int:
+    """How many options will itertools.combinations(iterable, r) yield?"""
+    n = len(iterable)
+    if r > n:
+        return 0
+    else:
+        return factorial(n) // factorial(r) // factorial(n - r)
+
+
+def len_permutations(iterable: Sized, r: int) -> int:
+    """How many options will itertools.permutations(iterable, r) yield?"""
+    n = len(iterable)
+    if r > n:
+        return 0
+    else:
+        return factorial(n) // factorial(n - r)