poj 1523 SPF 无向图关节点

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#include <stdio.h>#include <string.h>#include <iostream>#include <algorithm>#include <vector>#include <queue>#include <stack>#include <set>#include <map>#include <string>#include <math.h>#include <stdlib.h>#include <time.h>using namespace std;const int N=1000+5;int g[N][N],vis[N],low[N],dfn[N],sub[N],dep,n,son;void dfs(int u){    for(int v=1;v<=n;v++)    {        if(g[u][v])        {            if(!vis[v])            {                vis[v]=1;                dep++;                dfn[v]=low[v]=dep;                dfs(v);                low[u]=min(low[u],low[v]);                if(low[v]>=dfn[u])                {                    if(u==1) son++;                    else sub[u]++;                }            }            else              low[u]=min(low[u],dfn[v]);        }    }}int main(){    int i,j,u,v,flag,cas=0;    while(~scanf("%d",&u))    {        n=0;        n=max(n,u);        if(u==0) break;        memset(g,0,sizeof(g));        scanf("%d",&v);        n=max(n,v);        g[u][v]=g[v][u]=1;        while(~scanf("%d",&u))        {            if(u==0) break;            n=max(n,u);            scanf("%d",&v);            n=max(n,v);            g[u][v]=g[v][u]=1;        }        memset(vis,0,sizeof(vis));        memset(sub,0,sizeof(sub));        dep=1;        son=0;        dfn[1]=low[1]=vis[1]=1;        dfs(1);        if(son>1) sub[1]=son-1;        flag=0;        if(cas>0) printf("\n");        printf("Network #%d\n",++cas);        for(i=1;i<=n;i++)        {            //printf("%d\n",sub[i]);            if(sub[i])            {                flag=1;                printf("  SPF node %d leaves %d subnets\n",i,sub[i]+1);            }        }        if(!flag)            printf("  No SPF nodes\n");    }    return 0;}
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