From 7e7b56db42ceb8d2b8973eae678fa4b58d5d3659 Mon Sep 17 00:00:00 2001
From: Jesse Luehrs <doy@tozt.net>
Date: Wed, 13 May 2009 23:32:40 -0500
Subject: add old solutions

---
 15.lua | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 15.lua

(limited to '15.lua')

diff --git a/15.lua b/15.lua
new file mode 100644
index 0000000..8450302
--- /dev/null
+++ b/15.lua
@@ -0,0 +1,13 @@
+function combinations(n, r)
+    local numerator = 1
+    local denominator = 1
+    for i = n, n - r + 1, -1 do
+        numerator = numerator * i
+    end
+    for i = r, 1, -1 do
+        denominator = denominator * i
+    end
+    return numerator / denominator
+end
+
+print(combinations(40, 20))
-- 
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