HDU - 3652 B-number 数位dp

B-number

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 8375    Accepted Submission(s): 4977

 

Problem Description

A wqb-number, or B-number for short, is a non-negative integer whose decimal form contains the sub- string "13" and can be divided by 13. For example, 130 and 2613 are wqb-numbers, but 143 and 2639 are not. Your task is to calculate how many wqb-numbers from 1 to n for a given integer n.

 

Input

Process till EOF. In each line, there is one positive integer n(1 <= n <= 1000000000).

 

Output

Print each answer in a single line.

 

Sample Input

13 100 200 1000

 

Sample Output

1 1 2 2

 

#include<cstdio>
#include<cstring>
int s[10];int dp[10][13][3];

inline int dfs(int pos,int mod,int have,bool lim)
{
    if(pos<=0)return mod==0&&have==2;
    if(!lim&&dp[pos][mod][have]!=-1)return dp[pos][mod][have];
    int num=lim?s[pos]:9;int ans=0;
    for(int i=0;i<=num;i++)
    {
        int mod_x=(mod*10+i)%13;
        int have_x=have;
        if(have==0&&i==1)have_x=1;
        if(have==1&&i!=1)have_x=0;
        if(have==1&&i==3)have_x=2;
        ans+=dfs(pos-1,mod_x,have_x,lim&&i==num);
    }
    if(!lim)dp[pos][mod][have]=ans;
    return ans;
}

int main()
{
    int n;int t;
    while(scanf("%d",&n)!=EOF)
    {
        memset(s,0,sizeof(s));memset(dp,-1,sizeof(dp));t=0;
        while(n)
        {
            s[++t]=n%10;
            n/=10;
        }
        printf("%d\n",dfs(t,0,0,1));
    }
}