ZOJ1311(Network)

题目链接:传送门

题目大意:给你一副无向图，求有多少个割点

题目思路:tarjan算法（此题读入是字符串读入，需注意）

 #include <iostream>
 #include <cstdio>
 #include <cstdlib>
 #include <cmath>
 #include <algorithm>
 #include <cstring>
 #include <stack>
 #include <cctype>
 #include <queue>
 #include <string>
 #include <vector>
 #include <set>
 #include <map>
 #include <climits>
 #define lson root<<1,l,mid
 #define rson root<<1|1,mid+1,r
 #define fi first
 #define se second
 #define ping(x,y) ((x-y)*(x-y))
 #define mst(x,y) memset(x,y,sizeof(x))
 #define mcp(x,y) memcpy(x,y,sizeof(y))
 #define Min(x,y) (x<y?x:y)
 #define Max(x,y) (x>y?x:y)
 using namespace std;
 #define gamma 0.5772156649015328606065120
 #define MOD 1000000007
 #define inf 0x3f3f3f3f
 #define N 10005
 #define maxn 1000050
 typedef long long LL;
 typedef pair<int,int> PII;

 int n,m,ans,son;
 int pic[][];
 int low[],vis[],area[];
 int dfn[],deep;

 inline void init(){
     mst(area,);
     mst(vis,);
     mst(pic,);
     ans=son=;
     deep=;
     low[]=dfn[]=;
     vis[]=;
 }

 void dfs(int x){
    for(int i=;i<=n;++i)
     if(pic[x][i]){
         if(vis[i]){low[x]=min(low[x],dfn[i]);}
         else{
             vis[i]=;
             low[i]=dfn[i]=++deep;
             dfs(i);
             low[x]=min(low[x],low[i]);
             if(low[i]>=dfn[x]){
                 if(x==)++son;
                 else ++area[x];
             }
         }
     }
 }

 void read(){
     char str[];
     while(gets(str)){
         if(!strcmp("",str))break;
         int len=strlen(str);
         int i=,temp=;
         while(str[i]==' ')++i;
         while(isdigit(str[i])){
             temp=temp*+str[i]-'';
             ++i;
         }
         int x=temp;
         while(i<len){
             temp=;
             while(str[i]==' ')++i;
             while(isdigit(str[i])){
                 temp=temp*+str[i]-'';
                 ++i;
             }
             pic[x][temp]=pic[temp][x]=;
         }
     }
 }

 int main(){
     int i,j,group,Case=,x,y;
     while(scanf("%d",&n)!=EOF&&n){
         getchar();
         init();
         read();
         dfs();
         if(son>)++ans;
         for(i=;i<=n;++i)
             if(area[i])
                 ++ans;
         printf("%d\n",ans);
     }
     return ;
 }