Cod sursa(job #2075380)

Utilizator MaligMamaliga cu smantana Malig Data 25 noiembrie 2017 13:16:22
Problema 2SAT Scor 70
Compilator cpp Status done
Runda Arhiva educationala Marime 2.51 kb
#include <iostream>
#include <fstream>
#include <queue>
#include <cstdlib>

#if 1
#define pv(x) cout<<#x<<" = "<<x<<"; ";cout.flush()
#define pn cout<<endl
#else
#define pv(x)
#define pn
#endif

using namespace std;
ifstream in("2sat.in");
ofstream out("2sat.out");

#define ll long long
#define ull unsigned long long
#define pb push_back
#define mp make_pair
const int NMax = 2e5 + 5;
const int mod = 666013;

int N,M;
int aux[NMax],sol[NMax];
pair<int,int> ex[NMax];
vector< pair<int,int> > v[NMax];

bool use(int,int);
bool eval(int);
void cpy(int*,int*);

int main() {
    in>>N>>M;
    for (int i=1;i <= M;++i) {
        int x,y;

        in>>x>>y;
        ex[i] = mp(x,y);

        x = abs(x);
        y = abs(y);
        v[x].pb( mp(y,i) );
        v[y].pb( mp(x,i) );
    }

    for (int i=1;i <= N;++i) {
        sol[i] = -1;
    }

    bool ans = true;
    for (int i=1;i <= N;++i) {
        if (sol[i] != -1) {
            continue;
        }

        if (use(i,0) || use(i,1)) {
            cpy(sol,aux);
        }
        else {
            ans = false;
            break;
        }
    }

    if (ans) {
        for (int i=1;i <= N;++i) {
            out<<sol[i]<<' ';
        }
    }
    else {
        out<<"-1\n";
    }

    return 0;
}

bool use(int idx,int val) {
    cpy(aux,sol);

    aux[idx] = val;
    queue<int> Q;
    Q.push(idx);
    while (Q.size()) {
        int lit = Q.front();
        Q.pop();

        for (auto p : v[lit]) {
            int nxt = p.first, nrExp = p.second;

            if (aux[nxt] != -1) {
                if (eval(nrExp) == false) {
                    return false;
                }
                continue;
            }

            aux[nxt] = 0;
            bool canUse0 = eval(nrExp);

            aux[nxt] = 1;
            bool canUse1 = eval(nrExp);

            if (canUse0) {
                if (canUse1) {
                    aux[nxt] = -1;
                    continue;
                }
                aux[nxt] = 0;
            }
            else {
                aux[nxt] = 1;
            }
            Q.push(nxt);
        }
    }

    return true;
}

bool eval(int idx) {
    int x = ex[idx].first,
        y = ex[idx].second,
        val1 = aux[abs(x)],
        val2 = aux[abs(y)];

    if (x < 0) {val1 ^= 1;}
    if (y < 0) {val2 ^= 1;}

    return val1 | val2;
}

void cpy(int* a,int* b) {
    for (int i=1;i <= N;++i) {
        a[i] = b[i];
    }
}