POJ 1144 Network (strong connected components for cutting points)

Title Address: POJ 1144

Cut points. There are two ways to judge whether a point is a cut point:

If u is a cut point, when and only if the following 1 bars are satisfied

1, if u is the root, then you must have more than 1 subtrees tree

2, if you are not the root, then (u,v) for the branch edge, when Low[v]>=dfn[u].

Then according to these two sentences to find a cut point on it.

The code is as follows:

#include <iostream> #include <cstdio> #include <string> #include <cstring> #include < stdlib.h> #include <math.h> #include <ctype.h> #include <queue> #include <map> #include < Set> #include <algorithm>using namespace Std;int head[200], CNT, INDEX1, Ans;int vis[200], low[200], dfn[200], ge [200];struct node{int u, V, next;}    edge[2000];void Add (int u, int v) {edge[cnt].v=v;    Edge[cnt].next=head[u]; head[u]=cnt++;}    void Tarjan (int u, int fa) {int son=0, I;    Low[u]=dfn[u]=++index1;    Vis[u]=1;        for (i=head[u];i!=-1;i=edge[i].next) {int v=edge[i].v;        son++;            if (!vis[v]) {Tarjan (v,u);            Low[u]=min (Low[v],low[u]); if (u==1&&son>1| |            dfn[u]<=low[v]&&u!=1) {ge[u]++;    }} else if (V!=FA) low[u]=min (Low[u],dfn[v]);    }}void init () {memset (head,-1,sizeof (head));    cnt=0; Index1=ans= 0;    memset (vis,0,sizeof (VIS));    memset (dfn,0,sizeof (DFN)); memset (Ge,0,sizeof (GE));}    int main () {int n, I, J, u, V;        while (scanf ("%d", &n)!=eof&&n) {init (); while (scanf ("%d", &u)!=eof&&u) {while (GetChar ()! = ' \ n ') {scanf ("%d                ", &v);                Add (U,V);            Add (V,u);        }} Tarjan (1,-1);        for (i=1;i<=n;i++) {if (ge[i]) ans++;    } printf ("%d\n", ans); } return 0;}

POJ 1144 Network (strong connected components for cutting points)