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Cod sursa(job #520843)
#include <stdio.h>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
#define FOR(i, v) for(vector<int>::iterator i = v.begin(); i != v.end(); ++i)
#define NMAX 200010
vector <int> G[NMAX];
queue <int> q;
int SOL[NMAX], viz[NMAX];
int n, m;
int VAL, not_sol;
inline int real(int x){
if(x < 0) return n-x;
return x;
}
inline int other(int x){
if(x > n) return x-n;
return x+n;
}
void df(int x){
if(not_sol) return;
FOR(i, G[x])
if(!viz[*i]){
SOL[*i] = 1;
viz[*i] = viz[other(*i)] = 1;
df(other(*i));
q.push(*i);
}
else if(SOL[*i] == 0) {
not_sol = 1;
return;
}
}
int check(int y, int val){
VAL = val;
SOL[y] = val;
if(val == 1) y = other(y);
not_sol = 0;
df(y);
if(not_sol) return 0;
return 1;
}
void add(int x, int y){
G[real(x)].push_back(real(y));
G[real(y)].push_back(real(x));
}
void sterge(int x){
SOL[x] = SOL[other(x)] = viz[x] = viz[other(x)] = 0;
}
int main(){
freopen("2sat.in", "r", stdin);
freopen("2sat.out", "w", stdout);
scanf("%d%d", &n, &m);
for(int i = 1; i <= m; ++i){
int x, y;
scanf("%d%d", &x, &y);
add(x,y);
}
for(int i = 1; i <= n; ++i)
if(!viz[i]) {
if(!check(i, 1)){ //daca nu am solutie
while(!q.empty()) sterge(q.front()), q.pop(); //anulez atribuirile facute in check(i,1)
if(!check(i, 0)){
printf("-1\n");
return 0;
}
}
while(!q.empty()) q.pop(); //am solutie(atribuiri satisfiabile) deci golesc doar coada
}
for(int i = 1; i <= n; ++i)
printf("%d ", SOL[i]);
return 0;
}