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50 lines
1.2 KiB
50 lines
1.2 KiB
#include <bits/stdc++.h>
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using namespace std;
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const int N = 5e5 + 10, M = 4e6 + 10;
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// 链式前向星
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int e[M], h[N], idx, w[M], ne[M];
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void add(int a, int b, int c = 0) {
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e[idx] = b, ne[idx] = h[a], w[idx] = c, h[a] = idx++;
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}
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int dfn[N], low[N], ts, root;
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set<int> _set;
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void dfs(int u, int fa) {
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low[u] = dfn[u] = ++ts;
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int son = 0;
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for (int i = h[u]; ~i; i = ne[i]) {
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int v = e[i];
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if (v == fa) continue;
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if (!dfn[v]) {
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son++; // 儿子数量在割点时有用
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dfs(v, u);
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low[u] = min(low[u], low[v]);
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// 记录割点
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if (u != root && low[v] >= dfn[u]) _set.insert(u);
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if (u == root && son >= 2) _set.insert(u);
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} else
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low[u] = min(low[u], dfn[v]);
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}
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}
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int n, m;
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int main(void) {
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scanf("%d %d", &n, &m);
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// 链式前向星初始化
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memset(h, -1, sizeof h);
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while (m--) {
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int a, b;
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scanf("%d %d", &a, &b);
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add(a, b), add(b, a);
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}
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for (root = 1; root <= n; root++)
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if (!dfn[root]) dfs(root, -1);
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printf("%d\n", _set.size());
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for (auto i : _set) printf("%d ", i);
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return 0;
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} |