Add bin and edit workflow

2026-09-16 13:11:16 -06:00
parent c8ac4fcae5
commit 4cee170d66
17576 changed files with 895740 additions and 2 deletions
@@ -0,0 +1,37 @@
+module Math
+
+  # First 16 factorials.
+  FACTORIALS = [
+    1,
+    1,
+    2,
+    6,
+    24,
+    120,
+    720,
+    5_040,
+    40_320,
+    362_880,
+    3_628_800,
+    39_916_800,
+    479_001_600,
+    6_227_020_800,
+    87_178_291_200,
+    1_307_674_368_000
+  ]
+
+  # 1 * 2 * ... * +n+, <code>nil</code> for negative numbers
+  def self.factorial(n)
+    n = Integer(n)
+    if n < 0
+      nil
+    elsif FACTORIALS.length > n
+      FACTORIALS[n]
+    else
+      h = FACTORIALS.last
+      (FACTORIALS.length .. n).each { |i| FACTORIALS.push h *= i }
+      h
+    end
+  end
+
+end