HDUOJ-----Computer Transformation

Computer Transformation

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 4842    Accepted Submission(s): 1769

Problem Description

A sequence consisting of one digit, the number 1 is initially written into a computer. At each successive time step, the computer simultaneously tranforms each digit 0 into the sequence 1 0 and each digit 1 into the sequence 0 1. So, after the first time step, the sequence 0 1 is obtained; after the second, the sequence 1 0 0 1, after the third, the sequence 0 1 1 0 1 0 0 1 and so on.
How many pairs of consequitive zeroes will appear in the sequence after n steps?

 

Input

Every input line contains one natural number n (0 < n ≤1000).

 

Output

For each input n print the number of consecutive zeroes pairs that will appear in the sequence after n steps.

 

Sample Input

2

3

 

Sample Output

1

1

做这道题，纯粹是一道大数的题，当然你需要推导出这个公式f[n]=f[n-1]+2*f[n-2];

 #include<cstdio>
 const int maxn=;
 int arr[maxn+][]={};
 int len=;
 void LargeNum()
 {
      arr[][]=;
     for(int i=;i<=maxn;i++)
     {
         int c=;
         for(int j=;j<len;j++)
         {
           arr[i][j]+=arr[i-][j]+*arr[i-][j]+c;
           if(arr[i][len-]>)
               len++;
            c=arr[i][j]/;
              arr[i][j]%=;
         }
     }

 }
 int main( void )
 {
     int n,i;
     LargeNum();
     while(scanf("%d",&n)==)
     {
         if(n==)puts("");
         else
         {
         for(i=len;arr[n-][i]==;i--);
         for(int j=i;j>=;j--)
               printf("%d",arr[n-][j]);
         puts("");
         }
     }
     return ;
 }