EOJ 1821 Hanoi Tower III

http://acm.cs.ecnu.edu.cn/problem.php?problemid=1821

这题就等价于普通的汉诺塔，只是每一层移动两次，原来需要2^n - 1次，则现在需要2^(n + 1) - 2次，递推式为f(i) = 2 * f(i - 1) + 2

#include <iostream>
#include <cstdio>
using namespace std;
unsigned long long f[62];
int main()
{
    f[1] = 2;
    for (int i = 2; i < 62; i++)
        f[i] = f[i - 1] * 2 + 2;
    int n;
    while (cin >> n)
        cout << f[n] << endl;
    return 0;
}