#include<stdio.h>int sum(int n){	if(n>2)		return sum(n-1)+sum(n-2);	else		return n;}int main(){	int n;	while(scanf("%d",&n)!=EOF)	{		printf("%d\n",sum(n));	}	return 0;}这上面这种并没有通过，下面这个才是通过了的方法#include<iostream>int main(){	using namespace std;	__int64 a[51]={0,1,2},n;	for(int i=3;i<=50;i++)	    a[i]=a[i-1]+a[i-2];	while(cin>>n)	{		cout<<a[n]<<endl;	}}