汉诺塔III HDU - 2064

 1 #include<iostream>
 2 #include<stdio.h>
 3 #include<cstring>
 4 #include<queue>
 5 
 6 using namespace std;
 7 
 8 long long F(int num)    // 返回值较大时使用long long 
 9 {
10     if(num == 1)
11         return 2;
12     return 3*F(num-1)+2;
13 }
14 
15 int main()
16 {
17      int n;
18      while(scanf("%d", &n) != EOF)
19      {
20          printf("%lld\n", F(n));
21      }
22     
23     
24     return 0;
25 }