Submission #640172

#	Time	Username	Problem	Language	Result	Execution time	Memory
640172		colossal_pepe	Power Plant (JOI20_power)	C++17	100 / 100	548 ms	62496 KiB

power

#include <iostream>
#include <vector>
#include <map>
using namespace std;

int n;
vector<vector<int>> g;
string s;
vector<map<int, int>> dp;
vector<int> dp_sum;

int f(int a, int b) {
    return (s[a] == '1' ? max(1, dp_sum[a] - dp[a][b] - 1) : dp_sum[a] - dp[a][b]);
}

int dfs1(int u, int par) {
    dp[u][par] = 0;
    for (int v : g[u]) {
        if (v != par) {
            dp[u][v] = dfs1(v, u);
            dp_sum[u] += dp[u][v];
        }
    }
    return f(u, par);
}

void dfs2(int u, int par) {
    dp[u][par] = f(par, u);
    dp_sum[u] += dp[u][par];
    for (int v : g[u]) {
        if (v != par) dfs2(v, u);
    }
}

int solve() {
    dp.resize(n), dp_sum.resize(n, 0);
    for (int v : g[0]) {
        dp[0][v] += dfs1(v, 0);
        dp_sum[0] += dp[0][v];
    }
    for (int v : g[0]) {
        dfs2(v, 0);
    }
    int ans = 0;
    for (int u = 0; u < n; u++) {
        for (int v : g[u]) {
            ans = max(ans, f(u, v) + f(v, u));
        }
    }
    return ans;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n;
    g.resize(n);
    for (int i = 0; i < n - 1; i++) {
        int a, b;
        cin >> a >> b;
        a--, b--;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    cin >> s;
    cout << max(1, solve()) << '\n';
    return 0;
}

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