【HDOJ】1814 Peaceful Commission

2-SAT基础题目。

 /* 1814 */
 #include <iostream>
 #include <vector>
 #include <algorithm>
 #include <cstdio>
 #include <cstring>
 #include <cstdlib>
 using namespace std;

 #define MAXN 8005

 vector<int> vc[MAXN*];
 bool visit[MAXN*];
 int S[MAXN*], top;
 int n, m;

 bool dfs(int u) {
     if (visit[u^])    return false;
     if (visit[u])    return true;

     visit[u] = true;
     S[top++] = u;
     for (int i=; i<vc[u].size(); ++i) {
         if (!dfs(vc[u][i]))
             return false;
     }
     return true;
 }

 int main() {
     int ii, jj;
     int i, j, k;
     bool flag;

     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
     #endif

     while (scanf("%d %d", &n, &m) != EOF) {
         k = n+n;
         for (i=; i<k; ++i)
             vc[i].clear();
         memset(visit, false, sizeof(bool)*k);
         while (m--) {
             scanf("%d %d", &i, &j);
             --i;
             --j;
             ii = (i&) ? i-:i+;
             jj = (j&) ? j-:j+;
             vc[i].push_back(jj);
             vc[j].push_back(ii);
         }
         flag = true;
         for (i=; i<k; i+=) {
             if (! (visit[i]||visit[i+])) {
                 top = ;
                 if (!dfs(i)) {
                     while (top--)
                         visit[S[top]] = false;
                     if (!dfs(i+)) {
                         flag = false;
                         break;
                     }
                 }
             }
         }
         if (flag) {
             for (i=; i<k; ++i)
                 if (visit[i])
                     printf("%d\n", i+);
         } else {
             puts("NIE");
         }
     }

     return ;
 }