#include<iostream>
using namespace std;
int n;
unsigned long long ans=2;
int main()
{
	cin>>n;
	for(int i=1;i<=n-1;i++)
	{
		ans=ans*2;
	}
	cout<<ans-1;
	
	return 0;
}

这个程序40分

#include<iostream>
using namespace std;
int n;
unsigned long long ans=0;
void hanoi(int k,char x,char y,char z)
{
	if(k==0) return;
	hanoi(k-1,x,z,y);
	//cout<<k<<" "<<x<<" "<<y<<" "<<endl;
	ans++;
	hanoi(k-1,z,y,x);
}
int main()
{
	cin>>n;
	hanoi(n,'A','B','C');
	cout<<ans;
	
	return 0;
}

这个60分