Submission #404020

#	Time	Username	Problem	Language	Result	Execution time	Memory
404020		opukittpceno_hhr	Beads and wires (APIO14_beads)	C++17	0 / 100	4 ms	5016 KiB

beads

#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <string>
#include <cmath>
#include <cstdio>
#include <iomanip>
#include <fstream>
#include <cassert>
#include <cstring>
#include <unordered_set>
#include <unordered_map>
#include <numeric>
#include <ctime>
#include <bitset>
#include <complex>
#include <chrono>
#include <random>
#include <functional>

using namespace std;

#define int long long

const int INF = 1e18 + 239;
const int N = 2e5 + 7;

int to[N];
int dp[N][2];

vector<pair<int, int>> g[N];

void dfs(int cur, int p) {
    vector<int> sons;
    for (auto [t, w] : g[cur]) {
        if (t != p) {
            to[t] = w;
            sons.push_back(t);
            dfs(t, cur);
        }
    }
    if (sons.empty()) {
        dp[cur][0] = 0;
        dp[cur][1] = -INF;
        return;
    }
    dp[cur][0] = -INF;
    dp[cur][1] = -INF;
    //
    for (auto t : sons) {
        int c = 0;
        for (auto u : sons) {
            if (u == t) {
                c += dp[u][0];
                c += to[u];
            } else {
                c += max(dp[u][0], dp[u][1]);
            }
        }
        dp[cur][1] = max(dp[cur][1], c + to[cur]);
    }
    //
    {
        int c = 0;
        for (auto u : sons) {
             c += max(dp[u][0], dp[u][1]);
        }
        dp[cur][0] = max(dp[cur][0], c);
    }
    //
    sort(sons.begin(), sons.end(), [&](int f, int s) {
        return (dp[f][0] + to[f]) - max(dp[f][0], dp[f][1]) > (dp[s][0] + to[s]) - max(dp[s][0], dp[s][1]);
    });
    if (sons.size() > 1) {
        int c = dp[sons[0]][0] + dp[sons[1]][0] + to[sons[0]] + to[sons[1]];
        for (int i = 2; i < (int)sons.size(); i++) {
            c += max(dp[sons[i]][0], dp[sons[i]][1]);
        }
        dp[cur][0] = max(dp[cur][0], c);
    }
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int n;
    cin >> n;
    for (int i = 0; i + 1 < n; i++) {
        int u, v, w;
        cin >> u >> v >> w;
        u--;
        v--;
        g[u].push_back({v, w});
        g[v].push_back({u, w});
    }
    dfs(0, -1);
    cout << dp[0][0] << '\n';
}

• Subtask 1: 0 / 13
• Subtask 2: 0 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43