无向图连通度（割）

ACM模版

无向图连通度（割）

/* * INIT: edge[][]邻接矩阵；vis[],pre[],anc[],deg[]置为0； * CALL: dfs(0, -1, 1, n); * k = deg[0], deg[i] + 1(i = 1...n - 1)为删除该节点后得到的连通图个数 * 注意: 0作为根比较特殊 */const int V = 1010;int edge[V][V];int anc[V];int pre[V];int vis[V];int deg[V];void dfs(int cur, int father, int dep, int n){    //vertex:0 ~ n - 1    int cnt = 0;    vis[cur] = 1;    pre[cur] = anc[cur] = dep;    for (int i = 0; i < n; i++)    {        if (edge[cur][i])        {            if (i != father && 1 == vis[i])            {                if (pre[i] < anc[cur])                {                    anc[cur] = pre[i];  //back edge                }            }            if (0 == vis[i])            //tree edge            {                dfs(i, cur, dep + 1, n);                cnt++;  //分支个数                if (anc[i] < anc[cur])                {                    anc[cur] = anc[i];                }                if ((cur == 0 && cnt > 1) || (cnt != 0 && anc[i] >= pre[cur]))                {                    deg[cur]++; //link degree of a vertex                }            }        }    }    vis[cur] = 2;    return ;}