Cod sursa(job #1218970)

Utilizator smaraldaSmaranda Dinu smaralda Data 13 august 2014 00:26:37
Problema 2SAT Scor 80
Compilator cpp Status done
Runda Arhiva educationala Marime 1.64 kb
#include<stdio.h>
#include<string.h>
#include<vector>
#include<stack>
using namespace std;

const int NMAX = 2e5;

vector <int> graph[NMAX + 5], trans[NMAX + 5];
int n, vis[NMAX + 5], val[NMAX + 5];
stack <int> st;

inline int neg (int x) {
    return x <= n ? x + n : x - n;
}

void dfsPlus (int node) {
    vis[node] = 1;
    for(vector <int>::iterator it = graph[node].begin(); it != graph[node].end(); ++ it)
        if(!vis[*it])
            dfsPlus(*it);
    st.push(node);
}

void dfsMinus (int node) {
 //   fprintf(stderr, "%d ", node);
    vis[node] = vis[neg(node)] = 1;
    val[neg(node)] = 1;
    for(vector <int>::iterator it = trans[node].begin(); it != trans[node].end(); ++ it)
        if(!vis[*it])
            dfsMinus(*it);
}

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

    scanf("%d%d", &n, &m);
    for(i = 1; i <= m; ++ i) {
        scanf("%d%d", &a, &b);
        if(a < 0)
            a = -a + n;
        if(b < 0)
            b = -b + n;

        graph[neg(a)].push_back(b);
        graph[neg(b)].push_back(a);
        trans[b].push_back(neg(a));
        trans[a].push_back(neg(b));
    }

    for(i = 1; i <= 2 * n; ++ i)
        if(!vis[i])
            dfsPlus(i);

    memset(vis, 0, sizeof(vis));
    while(!st.empty()) {
        if(vis[st.top()] || vis[neg(st.top())]) {
            st.pop();
            continue;
        }

        dfsMinus(st.top());
       // fprintf(stderr, "\n", st.top());
       // for(i = 1; i <= n; ++ i)
         //   fprintf(stderr, "%d - %d ", i, vis[i]);
        st.pop();
    }

    for(i = 1; i <= n; ++ i)
        printf("%d ", val[i]);
    return 0;
}