POJ 1523

无向图求割点模板题

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <string.h>
 4 using namespace std;
 5 const int N=1002;
 6
 7 int subnets[N];
 8 int dfn[N],low[N];
 9 int count,mun,son,ks;
10
11 bool map[N][N];
12 bool vis[N];
13
14 void init(){
15     memset(map,0,sizeof(map));
16     for(int i=0;i<=N;++i){
17         vis[i]=dfn[i]=low[i]=subnets[i]=0;
18     }
19     count=1,son=0;
20     mun=0;
21     dfn[1]=low[1]=vis[1]=1;
22 }
23 void dfs(int x){
24     for(int i=1;i<=mun;i++){
25         if(map[x][i]){
26             if(!vis[i]){
27                 vis[i]=1;
28                 dfn[i]=low[i]=++count;
29                 dfs(i);
30                 low[x]=min(low[x],low[i]);
31                 if(low[i]>=dfn[x]){
32                     if(x==1)son++;
33                     else subnets[x]++;
34                 }
35             }
36             else low[x]=min(low[x],dfn[i]);
37         }
38     }
39 }
40 void print(){
41     bool yes=0;
42     if(son>1)subnets[1]=son-1;
43     printf("Network #%d\n",++ks);
44     for(int i=1;i<=mun;i++){
45         if(subnets[i]){
46             yes=1;
47             printf("  SPF node %d leaves %d subnets\n",i,subnets[i]+1);
48         }
49     }
50     if(!yes)printf("  No SPF nodes\n");
51     printf("\n");
52 }
53 int main(){
54     //freopen("test.txt","r",stdin);
55     int a,b;
56     ks=0;
57     while(scanf("%d",&a)&&a){
58         init();
59         scanf("%d",&b);
60         map[a][b]=map[b][a]=1;
61         mun=max(max(b,a),mun);
62         while(scanf("%d",&a)&&a){
63             scanf("%d",&b);
64             map[a][b]=map[b][a]=1;
65             mun=max(max(b,a),mun);
66         }
67         dfs(1);
68         print();
69     }
70     return 0;
71 }

POJ 1523