HDU_5456_数位dp

http://acm.hdu.edu.cn/showproblem.php?pid=5456

转化成a=b+c，dp[i][a][b][c]表示剩余i木棒，a是否有进位，b是否首尾，c是否首位，注意每次都要memset。

#include<iostream>
#include<cstring>
#include<cstdio>
#define LL long long
using namespace std;

int n,m,stick[] = {,,,,,,,,,};
LL dp[][][][];

LL dfs(int sum,int a,int b,int c)
{

    if(sum < ) return ;
    if(dp[sum][a][b][c] != -)  return dp[sum][a][b][c];
    if(b && c)
    {
        if(!a && sum == )  return ;
        if(a && sum == stick[])    return ;
    }
    if(sum == )    return ;
    LL& temp = dp[sum][a][b][c];
    temp = ;
    if(b ==  && c == )
    {
        for(int i = ;i <= ;i++)
        {
            for(int j = ;j <= ;j++)
            {
                int sub = stick[i]+stick[j]+stick[(i+j+a)%];
                temp += dfs(sum-sub,(i+j+a)/,,);
                if(i != )  temp += dfs(sum-sub,(i+j+a)/,,);
                if(j != )  temp += dfs(sum-sub,(i+j+a)/,,);
                if(i !=  && j != )    temp += dfs(sum-sub,(i+j+a)/,,);
                temp %= m;
            }
        }
    }
    else if(b == )
    {
        for(int i = ;i <= ;i++)
        {
            int sub = stick[i]+stick[(i+a)%];
            temp += dfs(sum-sub,(i+a)/,,);
            if(i != )  temp += dfs(sum-sub,(i+a)/,,);
            temp %= m;
        }
    }
    else if(c == )
    {
        for(int i = ;i <= ;i++)
        {
            int sub = stick[i]+stick[(i+a)%];
            temp += dfs(sum-sub,(i+a)/,,);
            if(i != )  temp += dfs(sum-sub,(i+a)/,,);
            temp %= m;
        }
    }
    temp %= m;
    return temp;
}
int main()
{
    int T;
    scanf("%d",&T);
    for(int i = ;i <= T;i++)
    {
        memset(dp,-,sizeof(dp));
        scanf("%d%d",&n,&m);
        printf("Case #%d: %lld\n",i,dfs(n-,,,));
    }
    return ;
}