bzoj1080

传送门:http://www.lydsy.com/JudgeOnline/problem.php?id=1080

神暴力,待搞懂.

代码

#include <cstdio>
#include <cmath>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
#include <map>
#include <queue>
#define ll long long
using namespace std;
typedef vector<int> ve;
map <ve,int> hash;
queue<ve>q;
string s[35];
int n;
void work()
{
    ve u,v,t;
    for (int i=1;i<=n;i++)
        if (s[i]=="")
        {
            printf("0");
            exit(0);
        }
        else u.push_back(i<<6);
    hash[u]=0;
    for(q.push(u);!q.empty();)
    {
        u=q.front();
        q.pop();
        int x=hash[u],cnt;
        for (int ch='0';ch<='1';ch++)
        {
            cnt=0;
            v.clear();
            for (int i=0;i<u.size();i++)
            {
                int which=u[i]>>6,where=u[i]&63;
                if (s[which][where]^ch) continue;
                if(++where==s[which].size()) {
                    ++cnt;
                for (int j=1;j<=n;j++)v.push_back(j << 6);
                }else v.push_back(which<<6|where);
            }
            if(cnt>=3)
            {
                printf("%d",x+1);
                exit(0);
            }
            sort(v.begin(),v.end());
            t.clear();
            for (int i=0;i<v.size();i++)
            {
                if(i<3||v[i]^v[i-3]) t.push_back(v[i]);
            }
            int &th=hash[t];
            if (t.size()&&!th) th=x+1,q.push(t);
        }
    }
    printf("-1");
}
int main()
{
    scanf("%d",&n);
    for (int i=1;i<=n;i++) cin>>s[i];
    work();
    return 0;
}