#include<bits/stdc++.h> using namespace std; #define ll long long #define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; i++) #define FORD(i, b, a) for (int i = (b), _a = (a); i >= _a; i--) #define pa pair<ll, ll> #define fi first #define se second #define bit(mask, j) ((mask >> j) & 1) const ll mod = 1e9 + 7; const ll INF = 1e18; //-------------------------------------------------------------------- const ll N = 2e5 + 10; ll n; vector<ll> g[N]; ll h[N], up[N][20]; ll f[N], c[N]; ll in[N], en[N], m, sz[N], arr[N]; void dfs(ll u, ll p) { f[u] += c[u]; in[u] = ++m; arr[m] = u; sz[u] = c[u]; for(auto v : g[u]) { if(v == p) continue; h[v] = h[u] + 1; f[v] = f[u]; up[v][0] = u; FOR(i, 1, 18) { up[v][i] = up[up[v][i - 1]][i - 1]; } dfs(v, u); sz[u] += sz[v]; } en[u] = m; } ll get(ll u, ll k) { for(int j = 0; (1 << j) <= k; j++) { if(bit(k, j)) u = up[u][j]; } return u; } ll lca(ll u, ll v) { if(h[u] < h[v]) swap(u, v); u = get(u, h[u] - h[v]); if(v == u) return u; FORD(i, 18, 0) { if(up[u][i] != up[v][i]) { u = up[u][i]; v = up[v][i]; } } return up[u][0]; } ll dist(ll u, ll v) { ll p = lca(u, v); return f[u] - f[v] + 2 * f[p] + c[p]; } bool dx[N]; void dfs2(ll u, ll p, ll &cur) { if(dx[u]) return; cur += c[u]; for(auto v : g[u]) { if(v == p) continue; dfs2(v, u, cur); } } void hbmt() { cin >> n; FOR(i, 1, n - 1) { ll u, v; cin >> u >> v; g[u].push_back(v); g[v].push_back(u); } ll cnt = 0; FOR(i, 1, n) { char x; cin >> x; c[i] = x - '0'; cnt += c[i]; } ll ans = 0; ans = min(cnt, 2LL); if(cnt == 0) { cout << 0; return; } dfs(1, 0); vector<ll> vt; FOR(i, 1, n) { ll u = arr[i]; if(c[u] == 1 && sz[u] <= 2) { vt.push_back(u); i = en[u]; } } sort(vt.begin(), vt.end(), [&] (ll &x, ll &y) { return in[x] < in[y]; }); ll p = vt[0]; FOR(i, 1, vt.size() - 1) { ll u = vt[i]; p = lca(p, u); } ll cur = sz[p]; dx[p] = 1; FOR(i, 0, vt.size() - 1) { ll u = vt[i]; cur -= sz[u]; } ll sz = vt.size(); cur = sz - cur; dfs2(1, 0, cur); cout << max(ans, cur); } int main() { ios_base::sync_with_stdio(0); cin.tie(0);cout.tie(0); #define NAME "hbmt" if(fopen(NAME".inp", "r")) { freopen(NAME".inp", "r", stdin); freopen(NAME".out", "w", stdout); } //int t;cin>>t;while(t--) hbmt(); return 0; }

power.cpp: In function 'int main()':
power.cpp:126:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  126 |                 freopen(NAME".inp", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
power.cpp:127:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  127 |                 freopen(NAME".out", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~