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https://git.sb/baoshuo/OI-codes.git
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59 lines
981 B
C++
59 lines
981 B
C++
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#include <iostream>
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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 t, n, k, x, y, a[N], siz[N], dis[N], ans;
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std::vector<int> g[N];
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void dfs(int u, int fa) {
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for (int v : g[u]) {
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if (v == fa) continue;
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dis[v] = dis[u] + 1;
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dfs(v, u);
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siz[u] += siz[v];
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ans += !!siz[v];
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}
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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 >> t;
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while (t--) {
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ans = 0;
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cin >> n >> k >> x >> y;
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siz[y] = 1;
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for (int i = 1; i <= k; i++) {
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cin >> a[i];
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siz[a[i]] = 1;
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}
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for (int i = 1, u, v; i < n; i++) {
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cin >> u >> v;
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g[u].push_back(v);
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g[v].push_back(u);
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}
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dfs(x, -1);
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cout << ans * 2 - dis[y] << endl;
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for (int i = 1; i <= n; i++) {
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g[i].clear();
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dis[i] = siz[i] = 0;
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}
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}
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return 0;
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}
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