Recursion example

recursion.cpp

int factorial_recursion(int n){
  if(n < 2){
    return 2;
  }
  return n * factorial_recursion(n-1)
}

int factorial(int n){
  int m = 1;
  for(int i = 2; i <= n; i++){
    m *= i;
  }
  return m;
}

int fibonacci_recursion(int n){
  if(n == 0){
    return 0;
  }
  if(n == 1){
    return 1;
  }
  
  return fibonacci_recursion(n-1) + fibonacci_recursion(n-2);
}

int fibonacci(n){
  int a = 0, b = 1;
  if(n == 0){
    return a;
  }
  
  for(int i = 0; i < n-1; i++){
    int tmp = b;
    b = a + b;
    a = tmp;
  }
  return b;
}