Submission #297787

#	Time	Username	Problem	Language	Result	Execution time	Memory
297787		eriksuenderhauf	Power Plant (JOI20_power)	C++17	100 / 100	245 ms	25704 KiB

power

#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
vector<int> adj[N];
int dp[N], rsm[N], sm[N], val[N];

int dfs(int u, int p = -1) {
  dp[u] = -val[u]; // don't cut
  for (int v: adj[u]) if (v != p)
    sm[u] += dfs(v, u);
  return dp[u] = max(-dp[u], dp[u] + sm[u]);
}

void reroot(int u, int p = -1) {
  rsm[u] = sm[u] + (~p ? max(val[p], -val[p] + rsm[p] - dp[u]) : 0);
  dp[u] = max(val[u], rsm[u] - val[u]);
  for (int v: adj[u]) if (v != p)
    reroot(v, u);
}

int main() {
  ios_base::sync_with_stdio(false); cin.tie(0);
  int n; cin >> n;
  for (int i = 1, u, v; i < n; i++) {
    cin >> u >> v; u--, v--;
    adj[u].push_back(v);
    adj[v].push_back(u);
  }
  string s; cin >> s;
  int ans = 0;
  for (int i = 0; i < n; i++)
    ans += val[i] = (s[i] == '1');
  ans = min(ans, 2);
  dfs(0);
  reroot(0);
  for (int i = 0; i < n; i++)
    ans = max(ans, dp[i]);
  cout << ans << "\n";
}

• Subtask 1: 6 / 6
• Subtask 2: 41 / 41
• Subtask 3: 53 / 53