hdu 2070

Your objective for this question is to develop a program which will generate a fibbonacci number. The fibbonacci function is defined as such:

f(0) = 0
f(1) = 1
f(n) = f(n-1) + f(n-2)

Your program should be able to handle values of n in the range 0 to 50.

Input

Each test case consists of one integer n in a single line where 0≤n≤50. The input is terminated by -1.

Output

Print out the answer in a single line for each test case.

Sample Input

3
4
5
-1

Sample Output

2
3
5


        
  
you can use 64bit integer: __int64

n大于40 小心了~。~ fib增长敲快的~简单的递归就不行啦(￣_,￣)   打表，记忆化搜索， 快速幂都可以 这次用的记忆化搜索

#include<iostream>
#include<string.h>
using namespace std;
long long f[55];
int n;
long long fib(int n)
{
    if(n==1)
    {
        f[n]=1;
    }
    if(n==0)
    {
        f[n]=0;
    }
    if(f[n]!=-1)return f[n];
    else
    {
        f[n]=fib(n-1)+fib(n-2);
    }
}
int main()
{

    memset(f,-1,sizeof(f));
    while(cin>>n&&n!=-1)
    {
        cout<<fib(n)<<endl;
    }
}