From 1b0d25c9769c0a02b233701234148373bef54613 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pau=20L=C3=B3pez=20N=C3=BA=C3=B1ez?=
 <paulopeznunez@gmail.com>
Date: Fri, 3 Oct 2025 04:10:43 +0200
Subject: [PATCH] Add ModularExponentiation function to math directory

This PR adds a function to compute (base^exponent) % mod efficiently in Kotlin
using iterative binary exponentiation. The function handles large exponents
without overflow issues. Example usage is included in the main() function.
---
 src/main/kotlin/ModularExponentiation.kt | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 src/main/kotlin/ModularExponentiation.kt

diff --git a/src/main/kotlin/ModularExponentiation.kt b/src/main/kotlin/ModularExponentiation.kt
new file mode 100644
index 0000000..41854ce
--- /dev/null
+++ b/src/main/kotlin/ModularExponentiation.kt
@@ -0,0 +1,19 @@
+fun modularExponentiation(base: Long, exponent: Long, mod: Long): Long {
+    var result = 1L
+    var b = base % mod
+    var e = exponent
+    while (e > 0) {
+        if (e % 2 == 1L) {
+            result = (result * b) % mod
+        }
+        b = (b * b) % mod
+        e /= 2
+    }
+    return result
+}
+
+// Test main function
+fun main() {
+    println("3^13 % 7 = ${modularExponentiation(3, 13, 7)}")  // Output: 3
+    println("5^117 % 19 = ${modularExponentiation(5, 117, 19)}") // Output: 1
+}