求去掉每一个割点后剩下几个连通分量
就求割点那个算法 里面加点东西就行
cnt[i]代表如果i是割点 去掉后会有几个连通分量
根节点要有2个或以上的的子树才是割点 根是割点 那么cnt[root] = child（子树的个数）不是割点cnt[root] = 0;
#include <cstdio>
#include <cstring>
#include <vector>
#include <stack>
#include <algorithm>
using namespace std;
const int maxn = 1010;
vector <int> a[maxn], bcc[maxn];
int pre[maxn];
int low[maxn];
bool iscut[maxn];
int bccno[maxn];
int cnt[maxn];
int dfs_clock;
int bcc_cnt;
int n;
struct Edge
{
int u, v;
};
stack <Edge> S;
int dfs(int u, int fa)
{
int lowu = pre[u] = ++dfs_clock;
int child = 0;
for(int i = 0; i < a[u].size(); i++)
{
int v = a[u][i];
Edge e = (Edge){u, v};
if(!pre[v])
{
S.push(e);
child++;
int lowv = dfs(v, u);
lowu = min(lowu, lowv);
if(lowv >= pre[u])
{
iscut[u] = true;
bcc_cnt++;
bcc[bcc_cnt].clear();
cnt[u]++;
while(1)
{
Edge x = S.top();
S.pop();
if(bccno[x.u] != bcc_cnt)
{
bcc[bcc_cnt].push_back(x.u);
bccno[x.u] = bcc_cnt;
}
if(bccno[x.v] != bcc_cnt)
{
bcc[bcc_cnt].push_back(x.v);
bccno[x.v] = bcc_cnt;
}
if(x.u == u && x.v == v)
break;
}
}
}
else if(pre[v] < pre[u] && v != fa)
{
S.push(e);
lowu = min(lowu, pre[v]);
}
}
if(fa < 0 && child == 1)
{
iscut[u] = false;
cnt[u] = 0;
}
if(fa < 0 && child > 1)
{
iscut[u] = true;
cnt[u] = child;
}
else if(cnt[u] > 0)
cnt[u]++;
return lowu;
}
void find_bcc()
{
memset(cnt, 0, sizeof(cnt));
memset(pre, 0, sizeof(pre));
memset(iscut, 0, sizeof(iscut));
memset(bccno, 0, sizeof(bccno));
dfs_clock = bcc_cnt = 0;
dfs(1, -1);
}
int main()
{
int u, v;
int cas = 0;
while(scanf("%d", &u) && u)
{
scanf("%d", &v);
n = 0;
n = max(n, u);
n = max(n, v);
for(int i = 1; i <= 1000; i++)
a[i].clear();
a[u].push_back(v);
a[v].push_back(u);
while(scanf("%d", &u) && u)
{
scanf("%d", &v);
a[u].push_back(v);
a[v].push_back(u);
n = max(n, u);
n = max(n, v);
}
find_bcc();
if(cas++)
puts("");
printf("Network #%d\n", cas);
int flag = 0;
for(int i = 1; i <= n; i++)
{
if(iscut[i])
{
printf(" SPF node %d leaves %d subnets\n", i, cnt[i]);
flag++;
}
}
if(!flag)
printf(" No SPF nodes\n");
//printf("\n");
}
return 0;
}