refactoring: simplified the zero cases

src/ggT/ggT.c

@@ -2,14 +2,9 @@
 
 
 int ggT(int a, int b){
-    // handles the case if both inputs are 0
-    if(a == 0 && b == 0){
-        return 0;
-    } else if(a == 0){      // handles the case if first number is 0
-        return b;
-    } else if(b == 0){      // handles the case if second number is 0
-        return a;
-    }
+    // handles the zero cases
+    if(a == 0) return b;
+    if(b == 0) return a;
 
     // Euclidean algorithm with modulo for getting the ggT
     while (b != 0) {