题解 | #N阶楼梯上楼问题#

#include <cstdio>
#include <iostream>
#include <string>

using namespace std;
const int MAX=91;

long long Fib[MAX];

int main(){
    Fib[0]=0;
    Fib[1]=1;
    Fib[2]=2;
    for(int i=3;i<MAX;i++){
        Fib[i]=Fib[i-1]+Fib[i-2];
    }
    int N;
    while(scanf("%d",&N)!=EOF){
        printf("%lld\n",Fib[N]);
    }
    return 0;
}