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@ -21,23 +21,15 @@ void dfs(int u, int fa) {
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for (int i = h[u]; ~i; i = ne[i]) { // 枚举u的每一条出边
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int v = e[i];
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if (v == fa) continue;
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dfs(v, u);
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sz[u] += sz[v];
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dfs(v, u); // 先把v为根的子树遍历完
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sz[u] += sz[v]; // 把 v中获取填充的sz[v]值，用于组装自己sz[u]
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son[u] = max(son[u], sz[v]);
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}
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son[u] = max(son[u], n - sz[u]);
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if ((son[u] << 1) <= n) r2 = r1, r1 = u;
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}
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/*
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1 2
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1 2
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1 3
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2 3
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*/
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signed main() {
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#ifndef ONLINE_JUDGE
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freopen("CF1406C.in", "r", stdin);
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#endif
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int T;
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cin >> T;
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while (T--) {
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