LightOj 1251 Forming the Council(2-sat)

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#include<stdio.h>#include<vector>#include<queue>#include<string.h>#include<stack>using namespace std;int m;int time;int low[20000];int dfn[20000];int cmp[20000];   int in[20000];int color[20000];int fp[20000];bool instack[20000];int count;int k;vector<int>edge[20000];vector<int>g[20000];void add_edge(int u,int v){int x=u,y=v;if(u<0) x=-u+m;if(v<0)y=-v+m;if(x>m) edge[x-m].push_back(y);else edge[x+m].push_back(y);if(y>m) edge[y-m].push_back(x);else edge[y+m].push_back(x);}stack<int>S;void tarjan(int u)   {dfn[u]=low[u]=++time;S.push(u);instack[u]=true;for(int i=0;i<edge[u].size();i++){int v=edge[u][i];if(dfn[v]==-1){tarjan(v);low[u]=min(low[u],low[v]);}else if(instack[v]){low[u]=min(dfn[v],low[u]);}}if(dfn[u]==low[u]){count++;int a;do{a=S.top();S.pop();cmp[a]=count;instack[a]=false;}while(a!=u);}}void suodian()                 //建新图 {memset(in,0,sizeof(in));for(int i=1;i<=count;i++)g[i].clear();for(int i=1;i<=2*m;i++){for(int j=0;j<edge[i].size();j++){int u=edge[i][j];if(cmp[i]!=cmp[u])      //反向建图 {g[cmp[u]].push_back(cmp[i]);in[cmp[i]]++;}}}}    void tpsort()                     {         memset(color,-1,sizeof(color));        int i,u;          queue<int>que;          for(i=1;i<=count;i++)          {              if(in[i]==0)              que.push(i);          //将入度为0的顶点加入队列          }          while(!que.empty())          {              u=que.front();              que.pop() ;            if(color[u]==-1)            {            color[u]=1;            color[fp[u]]=0;}            for(i=0;i<g[u].size();i++)              {                  int v=g[u][i];                  if(--in[v]==0)                   que.push(v);              }          }      }  void solve(){int res=0,i;count=0;time=0;memset(dfn,-1,sizeof(dfn));memset(cmp,-1,sizeof(cmp));memset(instack,false,sizeof(instack));for(i=1;i<=2*m;i++){if(dfn[i]==-1)tarjan(i);}printf("Case %d: ",++k);for(i=1;i<=m;i++){if(cmp[i]==cmp[i+m]){printf("No\n");return ;}else{fp[cmp[i]]=cmp[i+m];fp[cmp[i+m]]=cmp[i];}}suodian();tpsort();for(i=1;i<=m;i++){if(color[cmp[i]]==1)res++;}printf("Yes\n%d",res);for(i=1;i<=m;i++){if(color[cmp[i]]==1)printf(" %d",i);}printf("\n");}int main() {int i,t,n,u,v;scanf("%d",&t);while(t--){scanf("%d%d",&n,&m);for(i=1;i<=2*m;i++)edge[i].clear();for(i=0;i<n;i++){scanf("%d%d",&u,&v);add_edge(u,v);}solve();}return 0;}
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