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）
1 #include <iostream> 2 #include <cstdio> 3 #include <cstdlib> 4 #include <cmath> 5 #include <algorithm> 6 #include <cstring> 7 #include <stack> 8 #include <cctype> 9 #include <queue> 10 #include <string> 11 #include <vector> 12 #include <set> 13 #include <map> 14 #include <climits> 15 #define lson root<<1,l,mid 16 #define rson root<<1|1,mid+1,r 17 #define fi first 18 #define se second 19 #define ping(x,y) ((x-y)*(x-y)) 20 #define mst(x,y) memset(x,y,sizeof(x)) 21 #define mcp(x,y) memcpy(x,y,sizeof(y)) 22 #define Min(x,y) (x<y?x:y) 23 #define Max(x,y) (x>y?x:y) 24 using namespace std; 25 #define gamma 0.5772156649015328606065120 26 #define MOD 1000000007 27 #define inf 0x3f3f3f3f 28 #define N 10005 29 #define maxn 1000050 30 typedef long long LL; 31 typedef pair<int,int> PII; 32 33 int n,m,ans,son; 34 int pic[150][150]; 35 int low[150],vis[150],area[150]; 36 int dfn[150],deep; 37 38 inline void init(){ 39 mst(area,0); 40 mst(vis,0); 41 mst(pic,0); 42 ans=son=0; 43 deep=1; 44 low[1]=dfn[1]=1; 45 vis[1]=1; 46 } 47 48 void dfs(int x){ 49 for(int i=1;i<=n;++i) 50 if(pic[x][i]){ 51 if(vis[i]){low[x]=min(low[x],dfn[i]);} 52 else{ 53 vis[i]=1; 54 low[i]=dfn[i]=++deep; 55 dfs(i); 56 low[x]=min(low[x],low[i]); 57 if(low[i]>=dfn[x]){ 58 if(x==1)++son; 59 else ++area[x]; 60 } 61 } 62 } 63 } 64 65 void read(){ 66 char str[1000]; 67 while(gets(str)){ 68 if(!strcmp("0",str))break; 69 int len=strlen(str); 70 int i=0,temp=0; 71 while(str[i]==' ')++i; 72 while(isdigit(str[i])){ 73 temp=temp*10+str[i]-'0'; 74 ++i; 75 } 76 int x=temp; 77 while(i<len){ 78 temp=0; 79 while(str[i]==' ')++i; 80 while(isdigit(str[i])){ 81 temp=temp*10+str[i]-'0'; 82 ++i; 83 } 84 pic[x][temp]=pic[temp][x]=1; 85 } 86 } 87 } 88 89 int main(){ 90 int i,j,group,Case=0,x,y; 91 while(scanf("%d",&n)!=EOF&&n){ 92 getchar(); 93 init(); 94 read(); 95 dfs(1); 96 if(son>1)++ans; 97 for(i=1;i<=n;++i) 98 if(area[i]) 99 ++ans; 100 printf("%d ",ans); 101 } 102 return 0; 103 }