#include <stdio.h>

// Factorial
int iterativeFactorial(int n) {
  int factorial = 1; // why 1 not 0? refer to identity property of multiplication

  for (; n > 0; n--) {
    factorial *= n;
  }

  return factorial;
}

int recursiveFactorial(int n) {
  if (n < 1) {
    return 1;
  }

  return n * recursiveFactorial(n - 1);
}

// Positive Multiplication
int iterativeMultiplication(int x, int y) {
  int product = 0;

  for (; y >= 1; y--) {
    product += x;
  }

  return product;
}

int recursiveMultiplication(int x, int y) {
  if (y == 1) {
    return x;
  }

  return x + recursiveMultiplication(x, y - 1);
}

int main() {
  printf("[ITERATIVE ALGORITHMS]\n");
  printf("iterativeFactorial(3): %d\n", iterativeFactorial(3));
  printf("iterativeFactorial(5): %d\n", iterativeFactorial(5));
  printf("iterativeMultiplication(2, 3): %d\n", iterativeMultiplication(2, 3));
  printf("iterativeMultiplication(4, 6): %d\n", iterativeMultiplication(4, 6));

  printf("\n[RECURSIVE ALGORITHMS]\n");
  printf("recursiveFactorial(3): %d\n", recursiveFactorial(3));
  printf("recursiveFactorial(5): %d\n", recursiveFactorial(5));
  printf("recursiveMultiplication(2, 3): %d\n", recursiveMultiplication(2, 3));
  printf("recursiveMultiplication(4, 6): %d\n", recursiveMultiplication(4, 6));

  return 0;
}