用递归函数，一只母兔4岁后每年生一只小母兔，N年后有多少只？



帮帮忙，


谢谢了，

初学~献丑了
#include <iostream.h>
int tuzi(int x);
int main()
{
    int N;
    cout<<"please putin N=";
    cin>>N;
    cout<<"after "<<N<<" years:"<<tuzi(N)<<endl;
    return 0;
}
int tuzi(int x)
{
    if(x==0||x==1||x==2||x==3)
        return 1;
    
    return(tuzi(x-1)+tuzi(x-4));
}

//f(n)=f(n-1)+f(n-4)