求无向图的割顶和桥的裸题。

#include 
     
      #include 
      
       #include 
       
        using namespace std;const int maxn = 105, maxm = maxn * maxn;int n, m, tot, dfs_clock;int h[maxn], dfn[maxn], low[maxn], iscut[maxn]; struct edge{    int v, next;}a[maxm];void add(int x, int y){    a[tot].v = y;    a[tot].next = h[x];    h[x] = tot++;}int dfs(int u, int fa){    int lowu = dfn[u] = ++dfs_clock;    int child = 0;    for (int i = h[u]; ~i; i = a[i].next)    {        int v = a[i].v;        if (!dfn[v])        {            child++;            int lowv = dfs(v, u);            lowu = min(lowu, lowv);            if (lowv >= dfn[u])            {                iscut[u] = 1;            }//            if (lowv > dfn[u])//            {//                printf("%d - %d\n", u, v);//            }        }else if (dfn[v] < dfn[u] && v != fa)        {            lowu = min(lowu, dfn[v]);        }    }    if (fa == 0 && child == 1)    {        iscut[u] = 0;    }    low[u] = lowu;    return lowu;}int main(){//    freopen("poj1144.in","r",stdin);    while (scanf("%d", &n) && n)    {        memset(h, -1, sizeof h); tot = dfs_clock = 0;        memset(low, 0, sizeof low);        memset(dfn, 0, sizeof dfn);        memset(iscut, 0, sizeof iscut);        int x;        while (scanf("%d", &x) && x)        {            while (getchar() != '\n')            {                int y;                scanf("%d", &y);                add(x, y); add(y, x);            }        }        dfs(1, 0);        int ans = 0;        for (int i = 1; i <= n; i++)            if (iscut[i])                ans++;        printf("%d\n", ans);    }    return 0;}
       
      
     

恶心的地方在于读入，以及千万不要忘记初始化！！！