POJ1523 Targin求关节点

POJ1523 Targin求关节点
Targin求关节点

#include<queue>
#include<cstring>
#include<cstdio>
#include<algorithm>
using namespace std;
const int N = 1010;
struct node{
    int v, nxt;
}edge[2010];
int n, m, cnt, num, son;
int fir[N], low[N], dfn[N], s[N];
inline void add(int u, int v){
    edge[++cnt] = (node){v, fir[u]}; fir[u] = cnt;
    edge[++cnt] = (node){u, fir[v]}; fir[v] = cnt;
}
inline void dfs(int u){
    dfn[u] = low[u] = ++num;
    for(int i = fir[u]; i; i = edge[i].nxt){
        int v = edge[i].v;
        if(!dfn[v]){
            dfs(v);
            low[u] = min(low[u], low[v]);
            if(low[v] >= dfn[u]){
                if(u == m) son++;
                else s[u]++;
            }
        }
        else low[u] = min(low[u], dfn[v]);
    }
}
int main(){
    #ifdef ONLINE_JUDGE
    #else
        freopen("in.txt", "r", stdin);
    #endif // ONLINE_JUDGE
    int a, b, iCase = 1;
    bool flag;
    while(scanf("%d", &a), a){
        scanf("%d", &b);
        n = 0, m = 0x3f3f3f3f;
        cnt = 0;
        num = 0;
        son = 0;
        memset(fir, 0, sizeof(fir));
        memset(dfn, 0, sizeof(dfn));
        memset(s, 0, sizeof(s));
        n = max(n, max(a, b));
        m = min(m, min(a, b));
        add(a, b);
        while(scanf("%d", &a), a){
            scanf("%d", &b);
            n = max(n, max(a, b));
            m = min(m, min(a, b));
            add(a, b);
        }
        dfs(m);
        printf("Network #%d
", iCase++);
        s[m] = son - 1;
        flag = false;
        for(int i = 1; i <= n; i++){
            if(s[i]){
                printf("  SPF node %d leaves %d subnets
", i, s[i] + 1);
                flag = true;
            }
        }
        if(!flag){
            printf("  No SPF nodes
");
        }
        printf("
");
    }
    return 0;
}