poj 1166 The Clocks

http://poj.org/problem?id=1166

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<map>
#include<cmath>
#define LL long long

using namespace std;

const int N=11;

char pre[N][10]=
{"" ,"ABDE","ABC" ,"BCEF","ADG","BDEFH" ,"CFI" ,"DEGH" ,"GHI" ,"EFHI"};
int a[N];
int ans[N];
int b[N];
int num;
void judge(int k)
{
    for(int i=1;i<=9;++i)
    {
        if(a[i]%4!=0)
        return ;
    }
    for(int i=1;i<=9;++i)
    ans[i]=b[i];
    num=k;
    return ;
}
void dfs(int x,int sum)
{
    for(int i=0;i<4;++i)
    {
        b[x]=i;
        for(int j=0;pre[x][j]!='\0';++j)
        a[pre[x][j]-'A'+1]+=i;
        if(x<9&&sum<num)
        dfs(x+1,sum+i);
        if(x==9&&sum+i<num)
        {
            judge(sum+i);
        }
        for(int j=0;pre[x][j]!='\0';++j)
        a[pre[x][j]-'A'+1]-=i;
    }
}
int main()
{
    num=40;
    for(int i=1;i<=9;++i)
    {
        scanf("%d",&a[i]);
    }
    dfs(1,0);
    for(int i=1;i<=9;++i)
    {
        while(ans[i]--)
        {
            printf("%d ",i);
        }
    }
    printf("\n");
    return 0;
}