UVA-10319 - Manhattan(2-SAT)

2-sat题

 

// File Name: 10319.cpp
// Author: Zlbing
// Created Time: 2013/4/11 18:02:23

#include<iostream>
#include<string>
#include<algorithm>
#include<cstdlib>
#include<cstdio>
#include<set>
#include<map>
#include<vector>
#include<cstring>
#include<stack>
#include<cmath>
#include<queue>
using namespace std;
#define CL(x,v); memset(x,v,sizeof(x));
#define INF 0x3f3f3f3f
#define LL long long
#define REP(i,r,n) for(int i=r;i<=n;i++)
#define RREP(i,n,r) for(int i=n;i>=r;i--)

#define MAXN 100
struct TwoSAT{
    int n;
    vector<int>G[MAXN*2];
    bool mark[MAXN*2];
    stack<int>S;
    bool dfs(int x)
    {
        if(mark[x^1])return false;
        if(mark[x])return true;
        mark[x]=true;
        S.push(x);
        for(int i=0;i<G[x].size();i++)
        {
            int v=G[x][i];
            if(!dfs(v))return false;
        }
        return true;
    }
    void init(int _n)
    {
        n=_n;
        for(int i=0;i<2*n;i++)
            G[i].clear();
        memset(mark,0,sizeof(mark));
    }
    void add_clause(int x,int y)
    {
        G[x].push_back(y);
    }
    bool solve()
    {
        for(int i=0;i<2*n;i=i+2)
        {
            if(!mark[i]&&!mark[i+1]){
                  while(!S.empty())
                  {
                      S.pop();
                  }
                if(!dfs(i))
                {
                    while(!S.empty())
                    {
                        mark[S.top()]=false;
                        S.pop();
                    }
                    if(!dfs(i+1))return false;
                }
            }
        }
        
//        for(int i=0;i<2*n;i++)
//            if(mark[i])printf("%d ",T[i/2][i%2]);
//        printf("\n");
        return true;
    }
};
TwoSAT solver;

int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        int S,A,m;
        scanf("%d%d%d",&S,&A,&m);
        solver.init(S+A);
        int a1,s1,a2,s2;
        REP(i,1,m)
        {
            scanf("%d%d%d%d",&s1,&a1,&s2,&a2);
            s1--,a1--,s2--,a2--;
            a1*=2;s1=2*A+2*s1;a2*=2;s2=2*(A+s2);
            if(s1==s2&&a1==a2)continue;
            if(a2<a1)
            {
                s1=s1^1;
                s2=s2^1;
            }
            if(s2<s1)
            {
                a1^=1;
                a2^=1;
            }
            if(a1==a2)
            {
                solver.add_clause(a1^1,a2);
                continue;
            }
            if(s1==s2)
            {
                solver.add_clause(s1^1,s2);
                continue;
            }
            //printf("s1 %d\n a1 %d\ns2 %d\n a2 %d\n",s1,a1,s2,a2);
            solver.add_clause(a1^1,s1);
            solver.add_clause(s1^1,a1);
            solver.add_clause(a2^1,s2);
            solver.add_clause(s2^1,a2);
            solver.add_clause(a1^1,a2);
            solver.add_clause(s1^1,s2);
            solver.add_clause(a2^1,a1);
            solver.add_clause(s2^1,s1);
        }
        if(solver.solve())printf("Yes\n");
        else printf("No\n");
    }
    return 0;
}