POJ 1523 Tarjan求割点

来源：互联网发布：拔罐菲尔普斯知乎编辑：程序博客网时间：2024/05/17 01:43

思路：
Tarjan

        if(dfn[x]<=low[v[i]]){            if(x!=1)sub[x]++;            else S++;        }

//By SiriusRen#include <cstdio>#include <cstring>#include <algorithm>#define N 1005using namespace std;int xx,yy,first[N],next[N*N*2],v[N*N*2],tot,cnt,T,S,sub[N],f,cases;int dfn[N],low[N],vis[N];void add(int x,int y){v[tot]=y,next[tot]=first[x],first[x]=tot++;}void tarjan(int x,int fa){    dfn[x]=low[x]=++cnt;    for(int i=first[x];~i;i=next[i]){        if(!dfn[v[i]]){            tarjan(v[i],x);low[x]=min(low[x],low[v[i]]);            if(dfn[x]<=low[v[i]]){                if(x!=1)sub[x]++;                else S++;            }        }        else low[x]=min(low[x],dfn[v[i]]);    }}int main(){    memset(first,-1,sizeof(first));    while(scanf("%d",&xx)&&xx){        st:scanf("%d",&yy);        add(xx,yy),add(yy,xx);    }    tarjan(1,-1);    T=1;    printf("Network #%d\n",++cases);    if(S>1)sub[1]=S-1;    for(int i=1;i<=1000;i++)        if(sub[i])printf("  SPF node %d leaves %d subnets\n",i,sub[i]+1),f=1;    if(!f)puts("  No SPF nodes");    puts("");    scanf("%d",&xx);    if(xx==0)return 0;    else{        tot=cnt=S=f=0;        memset(sub,0,sizeof(sub));        memset(first,-1,sizeof(first));        memset(dfn,0,sizeof(dfn));        memset(vis,0,sizeof(vis));        goto st;    }}

这里写图片描述

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