#include <cstdio>
#include <iostream>
using namespace std;
#ifdef ONLINE_JUDGE
#define FINPUT(file) 0
#define FOUTPUT(file) 0
#else
#define FINPUT(file) freopen(file,"r",stdin)
#define FOUTPUT(file) freopen(file,"w",stdout)
#endif
int main()
{
FINPUT("in.txt");
FOUTPUT("out.txt");
int n;
while(cin>>n && n)
{
long long int f1 = 1;
long long int f2 = 2;
long long int f3 = 3;
int i = 4;
while(i<=n)
{
f1 = f2;
f2 = f3;
f3 = f1+f2;
i++;
}
if(n==1)
cout<<f1<<endl;
else if(n==2)
cout<<f2<<endl;
else if(n>=3)
cout<<f3<<endl;
}
return 0;
}原文地址:http://blog.csdn.net/daringpig/article/details/25552527