请问这个是怎么运行？

Question

#include <stdio.h>

int fan(int n)

{

 int k;

 if(n==0||n==1)

    return 3;

 else

    k=n-fan(n-2);

 return k;

}

int main()

{

 printf("%d\n", fan(9));

 return 0;

}

Answer 1

1、fun(9);
2、9-fun(7);
3、9-(7-fun(5));
4、9-(7-(5-fun(3)))
5、9-(7-(5-(3-fun(1)))) =>9-(7-(5-(3-3))) =7;