From 719e7dab9b56fe71bfb2cc7f58165164a9bf767e Mon Sep 17 00:00:00 2001
From: Aditya <bluenerd@protonmail.com>
Date: Tue, 13 Sep 2022 19:15:43 +0530
Subject: [PATCH] add factorial

---
 java/Stack/factorial.java | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 java/Stack/factorial.java

diff --git a/java/Stack/factorial.java b/java/Stack/factorial.java
new file mode 100644
index 0000000..c874535
--- /dev/null
+++ b/java/Stack/factorial.java
@@ -0,0 +1,19 @@
+class factorial {
+	/** @return n! */
+	static long fact(int n) {
+		// To fit n! in a long variable, require n < 21
+		assert (n >= 0) && (n <= 20) : "n out of range";
+		// Make a stack just big enough
+		Stack<Integer> S = new AStack<Integer>(n);
+		while (n > 1) S.push(n--);
+		long result = 1;
+		while (S.length() > 0)
+			result = result * S.pop();
+
+		return result;
+	}
+
+	public static void main(String[] args) {
+		System.out.println(fact(5));
+	}
+}