Submission #1199092

#	Time	Username	Problem	Language	Result	Execution time	Memory
1199092		AMel0n	Connecting Supertrees (IOI20_supertrees)	C++20	100 / 100	120 ms	22220 KiB

supertrees

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

typedef long long ll;
#define FOR(i,N) for(ll i = 0; i < N; i++)
#define all(x) (x).begin(), (x).end()
#define F first 
#define S second

#include "supertrees.h"

vector<int> par;
int find(int n) {
    if (n == par[n]) return par[n];
    return par[n] = find(par[n]);
}
void merge(int a, int b) {
    a = find(a);
    b = find(b);
    if (a == b) return ;
    par[b] = a;
}

int construct(vector<vector<int>> path) {
    int N = path.size();
    par.resize(N);
    iota(all(par), 0);

    
    FOR(i, N) {
        for (int j = i + 1; j < N; j++) {
            if (path[i][j] == 3) return 0; // bruh
            if (path[i][j] > 0) merge(i, j); 
        }
    }                

    FOR(i, N) {
        for (int j = i + 1; j < N; j++) {
            if (path[i][j] == 0 && find(i) == find(j)) return 0;
        }
    }


    vector<vector<int>> conn(N);
    FOR(i, N) conn[find(i)].push_back(i);


    iota(all(par), 0);
    FOR(i, N) {
        for (int j = i + 1; j < N; j++) {
            if (path[i][j] == 1) merge(i, j);
        }
    }

    FOR(i, N) {
        for (int j = i + 1; j < N; j++) {
            if (path[i][j] == 2 && find(i) == find(j)) return 0;
        }
    }
    
    vector<vector<int>> res(N, vector<int>(N));
    FOR(i, N) {
        if (i != find(i)) {
            res[i][find(i)] = 1;
            res[find(i)][i] = 1;
        }


        // if i is also in a path 2 component
        vector<int> c2;
        for (auto c: conn[i]) {
            if (c == find(c)) { 
                c2.push_back(c);
            }
        }
        if (c2.size() == 0) continue; 
        if (c2.size() == 1) continue; // either the parent of a path 1 component or only connected to a path 2 (uninitialised)
        if (c2.size() == 2) return 0; // can't have 2 paths between 2 elements in a component
        for (int j = 0; j < c2.size(); j++) {
            res[c2[j]][c2[(j+1)%c2.size()]] = 1;
            res[c2[(j+1)%c2.size()]][c2[j]] = 1;
        }
    }
    build(res);
    return 1;
}

// signed main() {
//     cin.tie(0); ios::sync_with_stdio(false);
    
// }

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