Cod sursa(job #1165929)

Utilizator poptibiPop Tiberiu poptibi Data 3 aprilie 2014 00:56:31
Problema 2SAT Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.49 kb
#include <cstdio>
#include <cstdlib>
#include <vector>
#include <algorithm>
using namespace std;

const int NMAX = 200010;

int N, M, X, Y, TopSort[NMAX], Sol[NMAX];
vector<int> G[NMAX], GT[NMAX];
bool Used[NMAX], NoSol;

int Neg(int X)
{
    if(X <= N) return X + N;
    return X - N;
}

void DFP(int Node)
{
    Used[Node] = 1;
    for(vector<int> :: iterator it = G[Node].begin(); it != G[Node].end(); ++ it)
        if(!Used[*it])
            DFP(*it);
    TopSort[++ TopSort[0]] = Node;
}

void DFM(int Node)
{
    if(Sol[Node] == 1) NoSol = 1;
    Sol[Neg(Node)] = 1;
    Used[Node] = 0;

    for(vector<int> :: iterator it = GT[Node].begin(); it != GT[Node].end(); ++ it)
        if(Used[*it])
            DFM(*it);
}

int main()
{
    freopen("2sat.in", "r", stdin);
    freopen("2sat.out", "w", stdout);

    scanf("%i %i", &N, &M);
    for(int i = 1; i <= M; ++ i)
    {
        scanf("%i %i", &X, &Y);
        if(X < 0) X = -X + N;
        if(Y < 0) Y = -Y + N;

        G[Neg(Y)].push_back(X);
        GT[X].push_back(Neg(Y));
        G[Neg(X)].push_back(Y);
        GT[Y].push_back(Neg(X));
    }

    for(int i = 1; i <= 2 * N; ++ i)
        if(!Used[i])
            DFP(i);

    reverse(TopSort + 1, TopSort + 2 * N + 1);

    for(int i = 1; i <= 2 * N; ++ i)
        if(Used[TopSort[i]] && Used[Neg(TopSort[i])])
            DFM(TopSort[i]);

    if(NoSol) printf("-1\n");
    else for(int i = 1; i <= N; ++ i) printf("%i ", Sol[i]);
}