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| #include <bits/stdc++.h>
using namespace std;
using LL = long long;
const int N = 1e6 + 1, M = N * 2;
int n, u, v;
int h[N], e[M], ne[M], idx, sz[N];
void add(int u, int v) {
e[++idx] = v, ne[idx] = h[u], h[u] = idx;
}
int main() {
scanf("%d", &n);
for (int i = 1; i < n; ++i) {
scanf("%d%d", &u, &v);
add(u, v), add(v, u);
}
int sum = 0;
function<void(int, int, int)> dfs = [&](int f, int u, int d) {
sz[u] = 1;
for (int i = h[u]; i; i = ne[i]) {
int v = e[i];
if (v != f) {
sum += d + 1;
dfs(u, v, d + 1);
sz[u] += sz[v];
}
}
};
dfs(0, 1, 0);
int ans = 1;
LL maxsum = sum;
function<void(int, int, LL)> reroot = [&](int f, int u, LL us) {
for (int i = h[u]; i; i = ne[i]) {
int v = e[i];
if (v != f) {
LL vs = us - sz[v] + (n - sz[v]);
if (maxsum < vs) maxsum = vs, ans = v;
reroot(u, v, vs);
}
}
};
reroot(0, 1, sum);
printf("%d\n", ans);
return 0;
}
|