【codevs 6162】Meronri爬楼梯

f[i]=2^(i-1)
下面是递推做法

#include<cstdio>#include<iostream>using namespace std;long long n;long long f[80],sum[80];int main(){    cin>>n;    f[1]=1;    sum[1]=1;    for(int i=2;i<=n;i++)    {        f[i]=sum[i-1]+1;        sum[i]=sum[i-1]+f[i];    }    printf("%I64d\n",f[n]);}