Submission #720645

#	Time	Username	Problem	Language	Result	Execution time	Memory
720645		Toxtaq	Connecting Supertrees (IOI20_supertrees)	C++17	19 / 100	239 ms	25988 KiB

supertrees

#ifndef SUPERTREES_H_INCLUDED
#define SUPERTREES_H_INCLUDED
#include "supertrees.h"
#include<bits/stdc++.h>
using namespace std;
struct DSU{
    vector<int>par;
    DSU(int n){
        par.assign(n, -1);
    }
    int FindRep(int u){
        if(par[u] < 0)return u;
        return par[u] = FindRep(par[u]);
    }
    void Union(int u, int v){
        u = FindRep(u);
        v = FindRep(v);
        if(u == v)return;
        if(par[u] > par[v])swap(u, v);
        par[u] += par[v];
        par[v] = u;
    }
    bool IsConnected(int u, int v){
        u = FindRep(u);
        v = FindRep(v);
        return (u == v);
    }
};
int N;
void build(vector<vector<int>>b);
vector<bool>vis;
vector<vector<int>>B;
vector<int>components;
void dfs(int u){
    components.push_back(u);
    vis[u] = 1;
    for(int i = 0;i < N;++i){
        if(B[u][i] && !vis[i]){
            dfs(i);
        }
    }
}
int construct(vector<vector<int>>p){
    N = p.size();
    DSU dsu1(N);
    vis.resize(N);
    B.assign(N, vector<int>(N));
    vector<vector<int>>ans(N, vector<int>(N));
    for(int i = 0;i < N;++i){
        for(int j = 0;j < N;++j){
            if(p[i][j] && i != j){
                if(dsu1.IsConnected(i, j))continue;
                dsu1.Union(i, j);
                B[i][j] = B[j][i] = 1;
            }
        }
    }
    for(int i = 0;i < N;++i){
        for(int j = 0;j < N;++j){
            if(i != j && !p[i][j] && dsu1.IsConnected(i, j))return 0;
        }
    }
    for(int i = 0;i < N;++i){
        int p = dsu1.FindRep(i);
        if(dsu1.par[p] == -2)return 0;
    }
    for(int i = 0;i < N;++i){
        if(!vis[i]){
            dfs(i);
            if(components.size() > 2){
                for(int j = 1;j < components.size();++j){
                    ans[components[j]][components[j - 1]] = ans[components[j - 1]][components[j]] = 1;
                }
                ans[components.back()][components[0]] = ans[components[0]][components.back()] = 1;
            }
            components.clear();
        }
    }
    build(ans);
    return 1;
}


#endif // SUPERTREES_H_INCLUDED

Compilation message (stderr)

supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:71:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |                 for(int j = 1;j < components.size();++j){
      |                               ~~^~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 10
• Subtask 3: 19 / 19
• Subtask 4: 0 / 35
• Subtask 5: 0 / 21
• Subtask 6: 0 / 4