hdu 3844 Mining Your Own Business

见刘汝佳训练指南P318
#pragma comment(linker, "/STACK:1024000000,1024000000")
#include <iostream>
#include <stack>
#include <queue>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <set>
#include <vector>
#include <cstring>
#include <algorithm>

#define INF 0x3fffffff
#define N 50010
#define M 1000010
#define LL long long
#define mod 95041567

using namespace std;

struct Node{
    int u, v;
    Node(int x = 0, int y = 0){ 
        u = x;
        v = y;
    }
};

Node G[N];
int dfs_clock, bcc_cnt, G_len;
int head[N], next[N * 2][2], pre[N], bccno[N];
bool iscut[N];
vector<int> bcc[N];

void init(int n){
    for(int i = 0; i <= n + 1; ++ i) 
        head[i] = -1, iscut[i] = 0, pre[i] = bccno[i] = 0;
    dfs_clock = bcc_cnt = G_len = 0;
}

void add(int u, int v){
    next[dfs_clock][1] = v;
    next[dfs_clock][0] = head[u];
    head[u] = dfs_clock ++;
}

int dfs(int u, int fa){
    int child = 0;
    pre[u] = ++ dfs_clock;
    int lowu = pre[u];
    for(int i = head[u]; i != -1; i = next[i][0]){
        int v = next[i][1];
        if(! pre[v]){
            G[G_len ++] = Node(u, v);
            ++ child;
            int lowv = dfs(v, u);
            lowu = min(lowu, lowv);
            if(lowv >= pre[u]){
                iscut[u] = true;
                bcc[++ bcc_cnt].clear();
                while(1){
                    Node k = G[-- G_len];
                    if(bccno[k.u] != bcc_cnt){
                        bcc[bcc_cnt].push_back(k.u);
                        bccno[k.u] = bcc_cnt;
                    }
                    if(bccno[k.v] != bcc_cnt){
                        bcc[bcc_cnt].push_back(k.v);
                        bccno[k.v] = bcc_cnt;
                    }
                    if(k.u == u && k.v == v) break;
                }
            }
        }
        else if(pre[u] > pre[v] && v != fa){
            G[G_len ++] = Node(u, v);
            lowu = min(lowu, pre[v]);
        }
    }
    if(fa < 0 && child == 1) iscut[u] = 0;
    return lowu;
}

int main()
{
  //  freopen("in.txt","r",stdin);
    int n, t = 0;
    while(scanf("%d", &n) != EOF){
        if(! n) break;
        init(n);
        int u, v;
        for(int i = 0; i < n; ++ i){
            scanf("%d %d", &u, &v);
            -- u, -- v;
            add(u, v);
            add(v, u);
        }
        dfs_clock = 0;
        dfs(0, -1);
        if(bcc_cnt == 1){
            LL c = bcc[1].size();
            printf("Case %d: 2 %I64d\n", ++t, c * (c - 1) / 2);
            continue;
        }
        v = 0;
        LL c = 1;
        for(int i = 1; i <= bcc_cnt; ++ i){
            int cnt = 0;
            for(int j = bcc[i].size() - 1; j >= 0 && cnt < 2; -- j)
                if(iscut[bcc[i][j]]) ++ cnt;
            if(cnt == 1) ++ v, c *= (LL)(bcc[i].size() - 1);
        }
        printf("Case %d: %d %I64d\n", ++t, v, c);
    }
    return 0;
}