【C语言】求第n个斐波那契数

#include<stdio.h>
long long int Fib(int n)
{
  if (n <= 2)
  return 1;
  else
  return Fib(n - 1) + Fib(n - 2);
}
int main()
{
    int num = 0;
  scanf("%d", &num);
  printf("%lld\n",Fib(num));
  return 0;
}

#include<stdio.h>
long long int Fib(int n)
{
  int a = 1;
  int b = 1;
  int c = 1;
  while (n > 2)
  {
  c = a + b;
  a = b;
  b = c;
  n--;
  }
  return c;
}
int main()
{
  int num=0;
  scanf("%d", &num);
  printf("%lld\n", Fib(num));
  return 0;
}