Fibonacci数列

#include<stdio.h>#include<time.h>int f(int n){if(n<=2)  return 1;else return f(n-1)+f(n-2);}void main(){double start,finish;int n;scanf("%d",&n);start=clock();printf("%d\n",f(n));finish=clock();printf("%f ms\n",difftime(finish,start));}