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 }
