hdu 2042 - 不容易系列之二

   1:  #include<stdlib.h>

   2:  #include<string.h>

   3:  #include<stdio.h>

   4:  #include<math.h>

   5:  #define N 31

   6:  int a[N]={3};

   7:  void init(){

   8:      int i;

   9:      for(i=1;i<N;i++){

  10:          a[i]=a[i-1]*2-2;//这个就是递推式

  11:      }

  12:  }

  13:  int main(){

  14:      int n,i;

  15:      init();

  16:      while(scanf("%d",&n)!=EOF){

  17:          while(n--){

  18:              int tmp;

  19:              scanf("%d",&tmp);

  20:              printf("%d\n",a[tmp]);

  21:          }

  22:      }

  23:  }