#include <bits/stdc++.h> using namespace std; const int MAXN = 2e5+5; vector<int> g[MAXN]; char special[MAXN]; int subsum[MAXN], dp[MAXN]; int n, ans; void predfs(int u, int p) { for (auto v : g[u]) { if (v == p) continue; predfs(v, u); subsum[u] += dp[v]; } dp[u] = subsum[u]; if (special[u] == '1') dp[u] = max(dp[u]-1, 1); // printf("idp %d %d\n", u, dp[u]); } void dfs(int u, int p) { if (special[u] == '1') { int cnt = 0; for (auto v : g[u]) cnt += dp[v] != 0; if (cnt <= 1) ans = max(subsum[u]+1, ans); else ans = max(dp[u], ans); } else { ans = max(ans, dp[u]); } // printf("dp %d %d %d %d\n", u, dp[u], subsum[u], ans); for (auto v : g[u]) { if (v == p) continue; int subu = subsum[u]; int subv = subsum[v]; int dpu = dp[u]; int dpv = dp[v]; subsum[u] -= dp[v]; dp[u] = subsum[u]; if (special[u] == '1') dp[u] = max(dp[u]-1, 1); subsum[v] += dp[u]; dp[v] = subsum[v]; if (special[v] == '1') dp[v] = max(dp[v]-1, 1); dfs(v, u); subsum[u] = subu; subsum[v] = subv; dp[u] = dpu; dp[v] = dpv; } } int main() { scanf("%d", &n); for(int i = 1; i <= n-1; i++) { int a, b; scanf("%d %d", &a, &b); g[a].push_back(b); g[b].push_back(a); } scanf(" %s", &special[1]); predfs(1, 1); dfs(1, 1); printf("%d\n", ans); }

power.cpp: In function 'int main()':
power.cpp:57:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   57 |  scanf("%d", &n);
      |  ~~~~~^~~~~~~~~~
power.cpp:60:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   60 |   scanf("%d %d", &a, &b);
      |   ~~~~~^~~~~~~~~~~~~~~~~
power.cpp:64:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   64 |  scanf(" %s", &special[1]);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~