Submission #296148

#	Time	Username	Problem	Language	Result	Execution time	Memory
296148		eriksuenderhauf	Power Plant (JOI20_power)	C++17	0 / 100	5 ms	4992 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];

string s;

void dfs(int u, int p = -1) {
  dp[u] = -(s[u] == '1'); // don't cut
  sm[u] = 0;
  for (int v: adj[u]) if (v != p) {
    dfs(v, u);
    sm[u] += dp[v];
  }
  dp[u] = max(-dp[u], dp[u] + sm[u]);
}

void reroot(int u, int p = -1) {
  if (~p) {
    int vp = s[p] == '1' ? 1 : 0;
    rsm[u] = sm[u] + max(vp, -vp + rsm[p] - dp[u]);
  } else {
    rsm[u] = sm[u];
  }
  int vu = s[u] == '1' ? 1 : 0;
  dp[u] = max(vu, rsm[u] - vu);
  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);
  }
  cin >> s;
  int ans = 0;
  dfs(0);
  reroot(0);
  for (int i = 0; i < n; i++)
    ans = max(ans, dp[i]);
  cout << ans << "\n";
}

• Subtask 1: 0 / 6
• Subtask 2: 0 / 41
• Subtask 3: 0 / 53