递推算法--求n层汉诺塔移动次数

#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
    /* 汉诺塔*/
    int a[100]={0,1};
    int n;
    cin>>n;

    for(int i = 2;i <= n; i++){
      a[i] = a[i - 1] * 2 + 1;
    }

    cout<<a[n]<<endl;

    return 0;
}