From 1c69e7fc1965d24cbfac9f97105c6106ab38f8a6 Mon Sep 17 00:00:00 2001
From: Ayush Raj <74952106+Ayush41@users.noreply.github.com>
Date: Sat, 11 Oct 2025 16:34:37 +0000
Subject: [PATCH 1/3] added factorial using recursion

---
 .../thealgorithms/recursion/Factorial.java    | 36 +++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 src/main/java/com/thealgorithms/recursion/Factorial.java

diff --git a/src/main/java/com/thealgorithms/recursion/Factorial.java b/src/main/java/com/thealgorithms/recursion/Factorial.java
new file mode 100644
index 000000000000..a4e1dd4dc815
--- /dev/null
+++ b/src/main/java/com/thealgorithms/recursion/Factorial.java
@@ -0,0 +1,36 @@
+package com.thealgorithms.recursion;
+
+/*
+    The Factorial of a non-negative integer n is the product of all positive integers less than or equal to n.
+    It is defined as:
+        n! = n × (n - 1) × (n - 2) × ... × 1
+    with the base case:
+        0! = 1
+
+    Example:
+        5! = 5 × 4 × 3 × 2 × 1 = 120
+*/
+
+public final class Factorial {
+
+    private Factorial() {
+        throw new UnsupportedOperationException("Utility class");
+    }
+
+    /**
+     * Computes the factorial of a non-negative integer using recursion.
+     *
+     * @param n the number for which factorial is to be calculated
+     * @return factorial of n
+     * @throws IllegalArgumentException if n is negative
+     */
+    public static long factorial(int n) {
+        if (n < 0) {
+            throw new IllegalArgumentException("Factorial is not defined for negative numbers.");
+        }
+        if (n == 0 || n == 1) {
+            return 1;
+        }
+        return n * factorial(n - 1);
+    }
+}

From aa8be9f1818fc6eff62036d91e5d18ef45143a87 Mon Sep 17 00:00:00 2001
From: Ayush Raj <74952106+Ayush41@users.noreply.github.com>
Date: Sat, 11 Oct 2025 16:37:40 +0000
Subject: [PATCH 2/3] factorail test

---
 .../recursion/FactorialTest.java              | 36 +++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 src/test/java/com/thealgorithms/recursion/FactorialTest.java

diff --git a/src/test/java/com/thealgorithms/recursion/FactorialTest.java b/src/test/java/com/thealgorithms/recursion/FactorialTest.java
new file mode 100644
index 000000000000..228cbf7c2ff4
--- /dev/null
+++ b/src/test/java/com/thealgorithms/recursion/FactorialTest.java
@@ -0,0 +1,36 @@
+package com.thealgorithms.recursion;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+public class FactorialTest {
+
+    @Test
+    public void testFactorialOfZero() {
+        assertEquals(1, Factorial.factorial(0));
+    }
+
+    @Test
+    public void testFactorialOfOne() {
+        assertEquals(1, Factorial.factorial(1));
+    }
+
+    @Test
+    public void testFactorialOfPositiveNumbers() {
+        assertEquals(120, Factorial.factorial(5));
+        assertEquals(720, Factorial.factorial(6));
+        assertEquals(5040, Factorial.factorial(7));
+    }
+
+    @Test
+    public void testFactorialOfTen() {
+        assertEquals(3628800, Factorial.factorial(10));
+    }
+
+    @Test
+    public void testNegativeNumberThrowsException() {
+        assertThrows(IllegalArgumentException.class, () -> Factorial.factorial(-1));
+    }
+}
\ No newline at end of file

From 2fb1dcb039f8f347a42885a3acdb0cbc08a8f43a Mon Sep 17 00:00:00 2001
From: Ayush Raj <74952106+Ayush41@users.noreply.github.com>
Date: Sat, 11 Oct 2025 16:57:39 +0000
Subject: [PATCH 3/3] feat: add Factorial algorithm using recursion

---
 .../thealgorithms/recursion/Factorial.java    | 42 +++++++--------
 .../recursion/FactorialTest.java              | 53 +++++++++----------
 2 files changed, 45 insertions(+), 50 deletions(-)

diff --git a/src/main/java/com/thealgorithms/recursion/Factorial.java b/src/main/java/com/thealgorithms/recursion/Factorial.java
index a4e1dd4dc815..63ffcf1feb96 100644
--- a/src/main/java/com/thealgorithms/recursion/Factorial.java
+++ b/src/main/java/com/thealgorithms/recursion/Factorial.java
@@ -1,36 +1,32 @@
 package com.thealgorithms.recursion;
 
 /*
-    The Factorial of a non-negative integer n is the product of all positive integers less than or equal to n.
-    It is defined as:
-        n! = n × (n - 1) × (n - 2) × ... × 1
-    with the base case:
-        0! = 1
+    The Factorial of a non-negative integer n is the product of all positive integers less than or
+   equal to n. It is defined as: n! = n × (n - 1) × (n - 2) × ... × 1 with the base case: 0! = 1
 
     Example:
         5! = 5 × 4 × 3 × 2 × 1 = 120
 */
 
 public final class Factorial {
+  private Factorial() {
+    throw new UnsupportedOperationException("Utility class");
+  }
 
-    private Factorial() {
-        throw new UnsupportedOperationException("Utility class");
+  /**
+   * Computes the factorial of a non-negative integer using recursion.
+   *
+   * @param n the number for which factorial is to be calculated
+   * @return factorial of n
+   * @throws IllegalArgumentException if n is negative
+   */
+  public static long factorial(int n) {
+    if (n < 0) {
+      throw new IllegalArgumentException("Factorial is not defined for negative numbers.");
     }
-
-    /**
-     * Computes the factorial of a non-negative integer using recursion.
-     *
-     * @param n the number for which factorial is to be calculated
-     * @return factorial of n
-     * @throws IllegalArgumentException if n is negative
-     */
-    public static long factorial(int n) {
-        if (n < 0) {
-            throw new IllegalArgumentException("Factorial is not defined for negative numbers.");
-        }
-        if (n == 0 || n == 1) {
-            return 1;
-        }
-        return n * factorial(n - 1);
+    if (n == 0 || n == 1) {
+      return 1;
     }
+    return n * factorial(n - 1);
+  }
 }
diff --git a/src/test/java/com/thealgorithms/recursion/FactorialTest.java b/src/test/java/com/thealgorithms/recursion/FactorialTest.java
index 228cbf7c2ff4..ac69bcfba152 100644
--- a/src/test/java/com/thealgorithms/recursion/FactorialTest.java
+++ b/src/test/java/com/thealgorithms/recursion/FactorialTest.java
@@ -6,31 +6,30 @@
 import org.junit.jupiter.api.Test;
 
 public class FactorialTest {
-
-    @Test
-    public void testFactorialOfZero() {
-        assertEquals(1, Factorial.factorial(0));
-    }
-
-    @Test
-    public void testFactorialOfOne() {
-        assertEquals(1, Factorial.factorial(1));
-    }
-
-    @Test
-    public void testFactorialOfPositiveNumbers() {
-        assertEquals(120, Factorial.factorial(5));
-        assertEquals(720, Factorial.factorial(6));
-        assertEquals(5040, Factorial.factorial(7));
-    }
-
-    @Test
-    public void testFactorialOfTen() {
-        assertEquals(3628800, Factorial.factorial(10));
-    }
-
-    @Test
-    public void testNegativeNumberThrowsException() {
-        assertThrows(IllegalArgumentException.class, () -> Factorial.factorial(-1));
-    }
+  @Test
+  public void testFactorialOfZero() {
+    assertEquals(1, Factorial.factorial(0));
+  }
+
+  @Test
+  public void testFactorialOfOne() {
+    assertEquals(1, Factorial.factorial(1));
+  }
+
+  @Test
+  public void testFactorialOfPositiveNumbers() {
+    assertEquals(120, Factorial.factorial(5));
+    assertEquals(720, Factorial.factorial(6));
+    assertEquals(5040, Factorial.factorial(7));
+  }
+
+  @Test
+  public void testFactorialOfTen() {
+    assertEquals(3628800, Factorial.factorial(10));
+  }
+
+  @Test
+  public void testNegativeNumberThrowsException() {
+    assertThrows(IllegalArgumentException.class, () -> Factorial.factorial(-1));
+  }
 }
\ No newline at end of file