Submission #404089

#	Time	Username	Problem	Language	Result	Execution time	Memory
404089		opukittpceno_hhr	Beads and wires (APIO14_beads)	C++17	28 / 100	1066 ms	5420 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;
    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]);
    });
    //
    {
        int c = dp[sons[0]][0] + to[sons[0]] + to[cur];
        for (int i = 1; i < (int)sons.size(); i++) {
            c += max(dp[sons[i]][0], dp[sons[i]][1]);
        }
        dp[cur][1] = max(dp[cur][1], c);
    }
    //
    {
        int c = 0;
        for (auto u : sons) {
            c += max(dp[u][0], dp[u][1]);
        }
        dp[cur][0] = max(dp[cur][0], c);
    }
    //
    // 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});
    }
    int ans = 0;
    for (int i = 0; i < n; i++) {
        dfs(i, -1);
        ans = max(ans, dp[i][0]);
    }
    cout << ans << '\n';
    // int root = 0;
    // dfs(root, -1);
    // cout << dp[root][0] << '\n';
}

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