Submission #1185106

#	Time	Username	Problem	Language	Result	Execution time	Memory
1185106		islam_2010	Connecting Supertrees (IOI20_supertrees)	C++20	100 / 100	129 ms	22236 KiB

supertrees

#include <bits/stdc++.h>
#include "supertrees.h"
using namespace std;

int find_par(int node, vector<int> &par) {
    if (node == par[node]) return node;
    return par[node] = find_par(par[node], par);
}

void unite(int a, int b, vector<int> &par, vector<vector<int>> &adj, vector<vector<int>> &groups) {
    a = find_par(a, par);
    b = find_par(b, par);
    if (a != b) {
        par[b] = a;
        adj[a][b] = adj[b][a] = 1;
        for (int x : groups[b]) groups[a].push_back(x);
        groups[b].clear();
    }
}

int construct(vector<vector<int>> p) {
    int n = p.size();
    vector<vector<int>> adj(n, vector<int>(n, 0));
    vector<int> par(n);
    iota(par.begin(), par.end(), 0);
    vector<vector<int>> groups(n);
    for (int i = 0; i < n; i++) groups[i].push_back(i);

    for (int i = 0; i < n; i++) {
        for (int j = i+1; j < n; j++) {
            if (p[i][j] == 1) {
                int a = find_par(i, par), b = find_par(j, par);
                if (a == b) continue;
                bool ok = true;
                for (int x : groups[a]) {
                    for (int y : groups[b]) {
                        if (p[x][y] != 1) ok = false;
                    }
                }
                if (!ok) return 0;
                unite(i, j, par, adj, groups);
            }
            if (p[i][j] == 3) return 0;
        }
    }

    vector<int> used(n, false);
    for (int i = 0; i < n; i++) {
        if (find_par(i, par) != i || used[i]) continue;

        vector<int> group;
        queue<int> q;
        q.push(i);
        used[i] = true;

        while (!q.empty()) {
            int cur = q.front(); q.pop();
            group.push_back(cur);
            for (int j = 0; j < n; j++) {
                if (find_par(j, par) == j && !used[j] && p[cur][j] == 2) {
                    q.push(j);
                    used[j] = true;
                }
            }
        }

        if (group.size() == 1) continue;
        if (group.size() == 2) return 0;

        for (int x = 0; x < group.size(); x++) {
            for (int y = x + 1; y < group.size(); y++) {
                for (int u : groups[group[x]]) {
                    for (int v : groups[group[y]]) {
                        if (p[u][v] != 2) return 0;
                    }
                }
            }
        }

        int m = group.size();
        for (int j = 0; j < m; j++) {
            int u = group[j], v = group[(j + 1) % m];
            adj[u][v] = adj[v][u] = 1;
        }
    }

    build(adj);
    return 1;
}

• Subtask 1: 11 / 11
• Subtask 2: 10 / 10
• Subtask 3: 19 / 19
• Subtask 4: 35 / 35
• Subtask 5: 21 / 21
• Subtask 6: 4 / 4