Submission #429524

#	Time	Username	Problem	Language	Result	Execution time	Memory
429524		dxz05	Power Plant (JOI20_power)	C++14	0 / 100	5 ms	5660 KiB

power

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
const int N = 222222;

mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());

vector<int> g[N];
int dp[N][2];
bool lamp[N];

void dfs(int v, int p){
    dp[v][1] = lamp[v];
    int sum = (lamp[v] ? -1 : 0);
    for (int u : g[v]){
        if (u == p) continue;
        dfs(u, v);
        if (lamp[u]){
            sum += max({1, dp[u][0], dp[u][1] - lamp[u]});
        } else sum += dp[u][0];
        dp[v][0] = max({dp[v][0], dp[u][0], dp[u][1]});
        dp[v][1] = max({dp[v][1], dp[u][0] + 1, dp[u][1]});
    }

    dp[v][0] = max(dp[v][0], sum - lamp[v]);
    if (!lamp[v]) dp[v][1] = 0;
}

void solve(){
    int n;
    cin >> n;

    for (int i = 1; i < n; i++){
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }

    string s;
    cin >> s;
    for (int i = 0; i < n; i++) lamp[i + 1] = s[i] == '1';

    dfs(1, 1);

    //for (int i = 1; i <= n; i++) cout << i << ' ' << dp[i][0] << ' ' << dp[i][1] << endl; cout << endl;

    cout << max(dp[1][0], dp[1][1]);

}

int main(){
    //freopen("output.txt", "w", stdout);
    int tests = 1;
    //cin >> tests;

    while (tests--){
        solve();
    }

    return 0;
}

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