1 // Swap 2 void Swap(int* a, int* b) 3 { 4     int tmp = *a; 5     *a = *b; 6     *b = tmp; 7 } 8  9 // GCD: Greatest Common Divisor10 int GCD(int i, int j)11 {12    if(i < 0 || j < 0)13       return 0;14 15    if(i < j)16       Swap(&i, &j); // Make sure i > j.17 18    if(j == 0) return i;19 20    return GCD(j, i % j);21 }22 23 // LCM: Lowest Common Multiple24 int LCM(int i, int j)25 {26    if(i < 0 || j < 0)27       return 0;28 29    return (i * j / GCD(i, j));30 }