From d099d8ee6048f473f48b0c211eeea2338bc7e70e Mon Sep 17 00:00:00 2001
From: cole <cole2247@gmail.com>
Date: Sat, 28 Dec 2019 01:10:53 -0500
Subject: [PATCH] feat: add euclidean algorithm implementation of gcd

---
 math/greatest_common_divisor_euclidean.cpp | 48 ++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 math/greatest_common_divisor_euclidean.cpp

diff --git a/math/greatest_common_divisor_euclidean.cpp b/math/greatest_common_divisor_euclidean.cpp
new file mode 100644
index 000000000..c4812e45b
--- /dev/null
+++ b/math/greatest_common_divisor_euclidean.cpp
@@ -0,0 +1,48 @@
+#include <cmath>
+#include <iostream>
+#include <stdexcept>
+
+// will find the greatest common denominator of two ints integers
+// Euclidean algorithm can be found here
+// https://en.wikipedia.org/wiki/Euclidean_algorithm
+int gcd(int num1, int num2) {
+    if (num1 <= 0 | num2 <= 0) {
+        throw std::domain_error("Euclidean algorithm domain is for ints > 0");
+    }
+
+    if (num1 == num2) {
+        return num1;
+    }
+
+    int base_num = 0;
+    int previous_remainder = 1;
+
+    if (num1 > num2) {
+        base_num = num1;
+        previous_remainder = num2;
+    } else {
+        base_num = num2;
+        previous_remainder = num1;
+    }
+
+    while ((base_num % previous_remainder) != 0) {
+        int old_base = base_num;
+        base_num = previous_remainder;
+        previous_remainder = old_base % previous_remainder;
+    }
+
+    return previous_remainder;
+}
+
+int main() {
+    std::cout << "gcd of 120,7 is " << (gcd(120, 7)) << std::endl;
+    try {
+        std::cout << "gcd of -120,10 is " << gcd(-120, 10) << std::endl;
+    } catch (const std::domain_error &e) {
+        std::cout << "Error handling was successful" << std::endl;
+    }
+    std::cout << "gcd of 312,221 is " << (gcd(312, 221)) << std::endl;
+    std::cout << "gcd of 289,204 is " << (gcd(289, 204)) << std::endl;
+
+    return 0;
+}