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https://git.sb/baoshuo/OI-codes.git
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115 lines
2.0 KiB
C++
115 lines
2.0 KiB
C++
#include <iostream>
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#include <algorithm>
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#include <set>
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#include <vector>
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using std::cin;
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using std::cout;
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const char endl = '\n';
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const int N = 2e5 + 5;
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int n, k, a[N], c[N];
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int cnt, id[N], fa[N], dep[N], siz[N], son[N], top[N];
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std::vector<int> g[N], color[N];
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std::set<int> ans;
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void dfs1(int u, int f) {
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siz[u] = 1;
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fa[u] = f;
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dep[u] = dep[f] + 1;
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for (int v : g[u]) {
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if (v == f) continue;
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dfs1(v, u);
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siz[u] += siz[v];
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if (siz[v] > siz[son[u]]) son[u] = v;
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}
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}
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void dfs2(int u, int t) {
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id[u] = ++cnt;
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top[u] = t;
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if (!son[u]) return;
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dfs2(son[u], t);
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for (int v : g[u]) {
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if (v == fa[u] || v == son[u]) continue;
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dfs2(v, v);
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}
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}
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int lca(int u, int v) {
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while (top[u] != top[v]) {
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if (dep[top[u]] < dep[top[v]]) std::swap(u, v);
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u = fa[top[u]];
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}
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return dep[u] < dep[v] ? u : v;
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}
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void dfs3(int u, int f) {
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for (int v : g[u]) {
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if (v == f) continue;
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dfs3(v, u);
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c[u] += c[v];
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}
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if (c[u] == 1) ans.emplace(a[u]);
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}
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int main() {
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std::ios::sync_with_stdio(false);
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cin.tie(nullptr);
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cin >> n >> k;
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for (int i = 1; i <= n; i++) {
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cin >> a[i];
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color[a[i]].emplace_back(i);
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}
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for (int i = 1, x, y; i < n; i++) {
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cin >> x >> y;
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g[x].emplace_back(y);
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g[y].emplace_back(x);
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}
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dfs1(1, 0);
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dfs2(1, 1);
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for (int i = 1; i <= k; i++) {
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std::sort(color[i].begin(), color[i].end(), [&](int x, int y) -> bool { return id[x] < id[y]; });
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int u = 0, p = 0;
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for (int v : color[i]) {
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if (!u) {
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u = p = v;
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c[v]++;
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} else {
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p = lca(u, v);
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c[v]++, c[p]--;
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}
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}
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c[fa[p]]--;
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}
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dfs3(1, 0);
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cout << ans.size() << endl;
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for (int x : ans) {
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cout << x << ' ';
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}
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cout << endl;
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return 0;
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}
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