Submission #518695

#	Time	Username	Problem	Language	Result	Execution time	Memory
518695		cig32	Power Plant (JOI20_power)	C++17	47 / 100	1565 ms	28228 KiB

power

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
const int MAXN = 3e5 + 10;
const int MOD = 1e9 + 7;
#define int long long
 
vector<int> adj[MAXN];
char c[MAXN];
int dp[MAXN];
int dpf(int node, int prev) {
  int sum = 0, mx = 0;
  for(int x: adj[node]) {
    if(x != prev) {
      int d = dpf(x, node);
      sum += d;
      mx = max(mx, d);
    }
  }
  if(prev == -1 && c[node] == '1') {
    return dp[node] = max(mx + 1, sum - 1);
  }
  if(prev == -1 && c[node] == '0') {
    return dp[node] = sum;
  }
  if(c[node] == '1') {
    return dp[node] = max(1ll, sum - 1);
  }
  else {
    return dp[node] = sum;
  }
}
int ans = 0;
void reroot(int x, int y) {
  dp[x] = (c[x] == '1' ? 1 : 0);
  int sum = 0, mx = 0;
  for(int z: adj[y]) {
    sum += dp[z];
    mx = max(mx, dp[z]);
  }
  dp[y] = (c[y] == '1' ? max(mx + 1, sum - 1) : sum);
}
void dfs(int node, int prev) {
  ans = max(ans, dp[node]);
  for(int x: adj[node]) {
    if(x != prev) {
      reroot(node, x);
      dfs(x, node);
      reroot(x, node);
    }
  }
}
void solve(int tc) {
  int N;
  cin >> N;
  for(int i=1; i<N; i++) {
    int a, b;
    cin >> a >> b;
    adj[a].push_back(b);
    adj[b].push_back(a);
  }
  if(N == 1) {
    cout << "1\n"; return;
  }
  for(int i=1; i<=N; i++) cin >> c[i];
  dpf(1, -1);
  dfs(1, -1);
  cout << ans << "\n";
}
 
int32_t main(){
  ios::sync_with_stdio(0); cin.tie(0);
  int t = 1; //cin >> t;
  for(int i=1; i<=t; i++) solve(i);
} 

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