Add GCDUsingEuclid class to compute GCD

Implemented the Euclidean algorithm for GCD calculation.

Author: Swati89923

src/main/java/com/thealgorithms/maths/GCDUsingEuclid.java

@@ -0,0 +1,38 @@
+package com.thealgorithms.maths;
+
+/**
+ * Euclidean algorithm to compute the Greatest Common Divisor (GCD).
+ * Wikipedia: https://en.wikipedia.org/wiki/Euclidean_algorithm
+ */
+public final class GCDUsingEuclid {
+
+    private GCDUsingEuclid() {
+        // Utility class
+    }
+
+    /**
+     * Computes GCD of two integers using Euclidean algorithm.
+     *
+     * @param a first integer
+     * @param b second integer
+     * @return gcd(a, b)
+     */
+    public static int gcd(int a, int b) {
+        a = Math.abs(a);
+        b = Math.abs(b);
+
+        if (a == 0) {
+            return b;
+        }
+        if (b == 0) {
+            return a;
+        }
+
+        while (b != 0) {
+            int remainder = a % b;
+            a = b;
+            b = remainder;
+        }
+        return a;
+    }
+}