【HDU 1269】迷宫城堡

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【HDU 1269】迷宫城堡
强联通模板要求全图只有一个强联通分量成立则Yes否则No

可能有一些独立的点所以要从头到尾遍历为此献了几个WA 节哀

代码如下

#include <cstdio>#include <cstdlib>#include <cstring>#include <vector>#include <stack>using namespace std;vector <int> head[11111];stack <int> s;int dfn[11111],low[11111];int vis[11111];int f,t,n,m;void Init(){    int i;    for(i = 1; i <= n; ++i)        head[i].clear();    t = f = 0;    memset(vis,0,sizeof(vis));    while(!s.empty()) s.pop();}void Tarjan(int u){    dfn[u] = low[u] = t++;    int i,v;    s.push(u);    vis[u] = -1;    for(i = 0; i < head[u].size(); ++i)    {        v = head[u][i];        if(!vis[v])        {            Tarjan(v);            if(f == 2) return;            low[u] = min(low[v],low[u]);        }        else if(vis[v] == -1)        {            low[u] = min(low[u],dfn[v]);        }    }    if(dfn[u] == low[u])    {        if(f)        {            f = 2;            return;        }        f = 1;        while(s.top() != u)        {            vis[s.top()] = 1;            s.pop();        }        vis[s.top()] = 1;        s.pop();    }}int main(){    int i,u,v;    while(~scanf("%d %d",&n,&m) && (m+n))    {        Init();        for(i = 0; i < m; ++i)        {            scanf("%d %d",&u,&v);            head[u].push_back(v);        }        for(i = 1; i <= n; ++i)            if(!vis[i])                Tarjan(i);        if(f == 1) printf("Yes\n");        else printf("No\n");    }    return 0;}

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