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50 lines
1.3 KiB
50 lines
1.3 KiB
2 years ago
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#include <bits/stdc++.h>
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using namespace std;
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const int maxn = 1e5 + 100;
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typedef long long LL;
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vector<LL> g[maxn];
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LL siz[maxn], son[maxn];
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LL r1, r2, n;
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void dfs(LL u, LL fa) {
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siz[u] = 1;
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son[u] = 0;
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for (LL i = 0; i < g[u].size(); i++) {
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LL v = g[u][i];
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if (v == fa) continue;
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dfs(v, u);
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siz[u] += siz[v];
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son[u] = max(son[u], siz[v]);
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}
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son[u] = max(son[u], n - siz[u]);
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if ((son[u] << 1) <= n) r2 = r1, r1 = u;
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}
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int main() {
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LL t;
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cin >> t;
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while (t--) {
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cin >> n;
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for (LL i = 0; i <= n + 10; i++) g[i].clear(), siz[i] = 0, son[i] = 0;
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for (LL i = 1; i < n; i++) {
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LL x, y;
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cin >> x >> y;
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g[x].push_back(y);
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g[y].push_back(x);
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}
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r1 = r2 = 0;
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dfs(1, 0);
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if (!r2) {
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LL r3 = g[r1][0];
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cout << r1 << " " << r3 << endl;
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cout << r1 << " " << r3 << endl;
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} else {
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LL r3 = r1;
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for (LL i = 0; i < g[r2].size(); i++) {
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r3 = g[r2][i];
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if (r3 != r1) break;
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}
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cout << r3 << " " << r2 << endl;
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cout << r3 << " " << r1 << endl;
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}
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}
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return 0;
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}
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