POJ 1144 & Uva 315 Network 【求割点数目】

#include <cmath>
#include <cstdio>
#include <string>
#include <cstring>
#include <sstream>
#include <iomanip>
#include <iostream>
#include <algorithm>
using namespace std;
//#pragma comment(linker, "/STACK:1024000000,1024000000")
#define FIN             freopen("input.txt","r",stdin)
#define FOUT            freopen("output.txt","w",stdout)
#define CASE(T)         for(scanf("%d",&T);T--;)
typedef long long LL;
const int maxn = 100 + 5;
const int maxm = 10000 + 5;
int N, ans;
bool Map[maxn][maxn];
struct Edge
{
    int to, next;
} edge[maxm];
int head[maxn], tot;
int Low[maxn], DFN[maxn];
int Index;
bool cut[maxn];
void AddEdge(int u, int v)
{
    edge[tot].to = v, edge[tot].next = head[u];
    head[u] = tot++;
}
void Tarjan(int u, int pre)
{
    int v;
    Low[u] = DFN[u] = ++Index;
    int son = 0;
    for(int i = head[u]; ~i; i = edge[i].next)
    {
        v = edge[i].to;
        if(v == pre) continue;
        if(!DFN[v])
        {
            son++;
            Tarjan(v, u);
            if(Low[u] > Low[v]) Low[u] = Low[v];
            if(u != pre && Low[v] >= DFN[u])
            {
                if(!cut[u]) ans++;
                cut[u] = true;
            }
        }
        else if(Low[u] > DFN[v]) Low[u] = DFN[v];
    }
    if(u == pre && son > 1)
    {
        if(!cut[u]) ans++;
        cut[u]  = true;
    }
}
void init()
{
    memset(Map, false, sizeof(Map));
    ans = 0;
    memset(head, -1, sizeof(head));
    tot = 0;
}
stringstream BUF;
string buf;
void Read_Graph()
{
    int a, b;
    while(1)
    {
        scanf("%d", &a);
        if(a == 0) break;
        getline(cin, buf);
        BUF.clear();
        BUF << buf;
        while(BUF >> b)
        {
            Map[a][b] = Map[b][a] = true;
        }
    }
    for(int i = 1; i <= N; i++)
    {
        for(int j = 1; j < i; j++)
        {
            if(Map[i][j])
            {
                AddEdge(i, j), AddEdge(j, i);
            }
        }
    }
}
void Solve()
{
    memset(DFN, 0, sizeof(DFN));
    memset(cut, false, sizeof(cut));
    Index = 0;
    for(int i = 1; i <= N; i++) if(!DFN[i])
        {
            Tarjan(i, i);
        }
    printf("%d\n", ans);
}
int main()
{
  //  FIN;
    while(~scanf("%d", &N), N)
    {
        init();
        Read_Graph();
        Solve();
    }
    return 0;
}

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