Cod sursa(job #2633626)

Utilizator stefan.popescuPopescu Stefan stefan.popescu Data 7 iulie 2020 22:17:08
Problema 2SAT Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.04 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <stack>
#include <algorithm>
using namespace std;
ifstream in ("2sat.in");
ofstream out("2sat.out");
int n, m, x, y, timp;
vector < vector <int> > muchii, componente;
vector <int> disc, low, componentaTata;
stack <int> stk;
vector <char> realVal;
inline int getPoz(int val) {return (val<0) ? -val: val+n;};
inline int getVal(int poz) {return (poz>n) ? poz-n: -poz;};
void tarjrec(int nod)
{
    low[nod]=disc[nod]=++timp;
    stk.push(nod);
    for(auto & x : muchii[nod])
    {
        if(disc[x]==-1)
        {
            tarjrec(x);
            low[nod]=min(low[nod], low[x]);
        }
        else
            low[nod]=min(low[nod], disc[x]);
    }
    if(low[nod]==disc[nod])
    {
        componente.push_back( vector<int>()); int val;
        do
        {
            val=stk.top(); stk.pop();
            componente.back().push_back(val);
            disc[val]=2*n+1;
            componentaTata[val]=componente.size();
        }while(val!=nod);
    }
}
inline void Tarjan()
{
    for(int i=1; i<=2*n; i++)
        if(disc[i]==-1)
            tarjrec(i);
}
int main()
{
    in>>n>>m;
    muchii.resize(2*n+1); componentaTata.resize(2*n+1);
    disc.resize(2*n+1, -1); low.resize(2*n+1);
    for(int i=1; i<=m; i++)
    {
        in>>x>>y;
        muchii[getPoz(-x)].push_back(getPoz(y));
        muchii[getPoz(-y)].push_back(getPoz(x));
    }
    Tarjan(); muchii.clear(); low.clear(); disc.clear();
    muchii.shrink_to_fit(); disc.shrink_to_fit(); low.shrink_to_fit();

    realVal.resize(2*n+1, 0);

    for(int i=1; i<=n; i++)
        if(componentaTata[i]==componentaTata[i+n])
        {out<<"-1"; return 0;}

    for(auto itr=componente.rbegin(); itr!=componente.rend(); itr++)
        for(auto itr2=itr->begin(); itr2!=itr->end(); itr2++)
            if(realVal[getPoz(-getVal(*itr2))]==0)
                realVal[*itr2]=1, realVal[*itr2+n]=2;

    for(int i=1; i<=n; i++)
        out<<(bool) (realVal[i+n]-1)<<"\n";

    return 0;
}