自己寫的代碼

using namespace std; const int maxn = 1e6; int head[maxn]; int DFN[maxn],LOW[maxn],stk[maxn],visit[maxn],belong[maxn]; vector<int> scc[maxn]; int tot,idx,cnt,sccnum; int n,color[maxn],degree[maxn],pos[maxn]; struct Es{ int v; int next; int cost; }Es[maxn<<1]; vector<int> bkG[maxn]; void init(){ sccnum = tot = idx = cnt = 0; memset(head,-1,sizeof(head)); memset(DFN,0,sizeof(DFN)); memset(LOW,0,sizeof(LOW)); memset(visit,0,sizeof(visit)); memset(color,0,sizeof(color)); memset(degree,0,sizeof(degree));memset(pos,0,sizeof(pos));for(int i = 0;i < maxn;i++) scc[i].clear();for(int i = 0;i < maxn;++i) bkG[i].clear(); } inline void add_edge(int i,int j,int cost = 1){ Es[cnt].v = j; Es[cnt].cost = cost; Es[cnt].next = head[i]; head[i] = cnt++; } void tarjan(int x) {DFN[x]=LOW[x]=++tot;stk[++idx]=x;visit[x]=1;for(int i=head[x];i!=-1;i=Es[i].next){if(!DFN[Es[i].v]) {tarjan(Es[i].v);LOW[x] = min(LOW[x],LOW[Es[i].v]);}else if(visit[Es[i].v ]){ LOW[x] = min(LOW[x],DFN[Es[i].v]);}}if(LOW[x]==DFN[x]){++sccnum;do{int item = stk[idx];belong[item] = sccnum;scc[sccnum].push_back(item);visit[item]=0;idx--;}while(x!=stk[idx+1]);}return ; } bool check(){for(int i = 1;i <= n;i++){if(belong[i] == belong[i+n]) return false;}return true; } bool solve(){for(int i = 1;i <= 2*n;++i )if(!DFN[i]) tarjan(i);if(!check()) return false;for(int i = 1;i <= n;++i){if(!pos[belong[i]]){pos[belong[i]] = belong[i+n];pos[belong[i+n]] = belong[i];}}for(int i = 1;i <= 2*n;++i){for(int e = head[i];e != -1;e = Es[e].next){int v = Es[e].v;if(belong[i] != belong[v]){degree[belong[i]]++;bkG[belong[v]].push_back(belong[i]);}}}queue<int> que;for(int i = 1;i <= sccnum;++i){if(!degree[i])que.push(i);}while(!que.empty()){int u = que.front();que.pop();if(!color[u]){color[u] = 1;color[pos[u]] = 2;}for(int i = 0;i < bkG[u].size();++i){int v = bkG[u][i];degree[v]--;if(!degree[v])que.push(v);}}//在這里準備輸出答案//為1表示選中，為2表示為選中/*for(int i = 1;i <= n;++i){if(color[belong[i]] == 1) {//Yes}else{//No}} */return true; }
//使用方法

1.init()

2.用add_edge建圖

3.用solve()函數求解

總結

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