HDU 1041 Computer Transformation 大数递推

Computer Transformation

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)

Total Submission(s): 5787 Accepted Submission(s): 2090

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

[code]

/*
要学会分析题目啊。。。。。
00的产生必然由n-1组的01产生，即00的个数等于n-1组01的个数。
n-1组01的产生有两个来源。
1).由n-2组的1
2).由n-2组的00变幻1010，
其中一个00只能产生一个01.这个就是要求的n-2连续的个数 

可以推出第n组00的个数dp
=dp[n-2]+第n-2组1的个数(2^((n-2)-1)); 
发现还要用大数 
*/

#include<iostream>
#include<cstring>
using namespace std;

int dp[1002][500];//因为两个长度 比较麻烦 直接500 不记长度 
int p[500];
int main(){
    
    int n,i,j,z,t;
    
    memset(p,0,sizeof(p));
    memset(dp,0,sizeof(dp));
    dp[1][1]=0;
    dp[2][1]=1;
    dp[3][1]=1;
    
    p[1]=1; 

    for(i=4;i<1001;i++)
    {
        for(j=1;j<500;j++)//处理2的多次方    
            p[j]=p[j]*2;
        z=0;
        for(j=1;j<500;j++)    
        {
            t=p[j]+z;
            z=t/10;
            p[j]=t%10;
        }
            
        for(j=1;j<500;j++)//处理递推方程 
            dp[i][j]=dp[i-2][j]+p[j];
            
        z=0;
        for(j=1;j<500;j++)    
        {
            t=dp[i][j]+z;
            z=t/10;
            dp[i][j]=t%10;
        }
    }
    while(cin>>n)
    {
        i=499;
        while(dp
[i]==0) i--;
        for(;i>=1;i--)
            printf("%d",dp
[i]);
        if(n!=1)
            printf("\n");
        else 
            printf("0\n");
    }
    return 0;
}