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@ -1,41 +1,37 @@
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#include <bits/stdc++.h>
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using namespace std;
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const int N = 200010, M = N << 1;
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#define int long long
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#define endl "\n"
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const int N = 200010, M = N << 1;
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int n;
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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 n;
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int f[N];
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int g[N];
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int sz[N], f[N], g[N], ans;
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// 第一次dfs,向下向上，生成汇总信息
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void dfs1(int u, int fa) {
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f[u] = 1; // 以u为根的子树大小，初始时有u一个节点，sz[u]=1
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sz[u] = 1;
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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) {
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// 先填充子孙节点的统计信息
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dfs1(v, u);
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// 利用子孙节点的统计信息，汇总生成u节点的连通块节点个数统计信息
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f[u] += f[v];
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}
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if (v == fa) continue;
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dfs1(v, u);
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sz[u] += sz[v];
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f[u] += f[v];
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}
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f[u] += sz[u];
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}
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// 第二次dfs,向上向下
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void dfs2(int u, int fa) {
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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) {
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g[v] = g[u] + f[1] - 2 * f[v];
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dfs2(v, u);
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}
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if (v == fa) continue;
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g[v] = n - sz[v] + g[u] - sz[v];
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dfs2(v, u);
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}
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}
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@ -49,16 +45,10 @@ signed main() {
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cin >> a >> b;
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add(a, b), add(b, a);
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}
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dfs1(1, 0);
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// 这是啥？
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for (int i = 1; i <= n; i++) g[1] += f[i];
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g[1] = f[1];
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dfs2(1, 0);
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int ans = 0;
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for (int i = 1; i <= n; i++) ans = max(ans, g[i]);
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cout << ans << endl;
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}
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