Submission #964044

#	Time	Username	Problem	Language	Result	Execution time	Memory
964044		SuPythony	Connecting Supertrees (IOI20_supertrees)	C++17	11 / 100	164 ms	24224 KiB

supertrees

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

class DSU {
    vector<int> par;
    vector<int> siz;

public:
    DSU(int n) {
        par.resize(n);
        iota(par.begin(),par.end(),0);
        siz.assign(n,1);
    }

    int find_set(int u) {
        if (par[u]==u) return u;
        return par[u]=find_set(par[u]);
    }

    bool is_same(int u, int v) {
        return find_set(u)==find_set(v);
    }

    bool unite_set(int u, int v) {
        u=find_set(u);
        v=find_set(v);
        if (u==v) return false;
        if (siz[u]<siz[v]) swap(u,v);
        par[v]=u;
        siz[u]+=siz[v];
        return true;
    }
};

int construct(vector<vector<int>> p) {
    int n = p.size();
    vector<vector<int>> ans(n,vector<int>(n,0));
    DSU dsu1=DSU(n);
    DSU dsu2=DSU(n);
    for (int i=0; i<n; i++) {
        for (int j=0; j<n; j++) {
            if (i==j) continue;
            if (p[i][j]==1) {
                if (dsu1.unite_set(i,j)) {
                    ans[i][j]=1;
                    ans[j][i]=1;
                }
            }
            if (p[i][j]==2) {
                dsu2.unite_set(i,j);
            }
        }
    }
//    for (int i=0; i<n; i++) {
//        for (int j=0; j<n; j++) {
//            if (p[i][j]==0&&(dsu1.is_same(i,j)||dsu2.is_same(i,j))) {
//                return 0;
//            }
//            if (p[i][j]==1) {
//                if (dsu2.is_same(i,j)) return 0;
//            }
//            if (p[i][j]==2) {
//                if (dsu1.is_same(i,j)) return 0;
//            }
//        }
//    }
    unordered_map<int,vector<int>> m;
    for (int i=0; i<n; i++) {
        int s=dsu2.find_set(i);
        bool found=false;
        for (int j=0; j<n; j++) {
            if (i==j) continue;
            if (p[i][j]==1&&dsu2.find_set(j)==s) {
                p[i][j]=45445;
                p[j][i]=46556;
                found=true;
                break;
            }
        }
        if (found) continue;
        m[s].push_back(i);
    }
    for (auto i: m) {
        vector<int> v=i.second;
        if (v.size()==1||v.size()==0) continue;
        if (v.size()==2) return 0;
        ans[v.front()][v.back()]=1;
        ans[v.back()][v.front()]=1;
        for (int j=0; j<v.size()-1; j++) {
            ans[v[j]][v[j+1]]=1;
            ans[v[j+1]][v[j]]=1;
        }
    }
//    for (auto i: ans) {
//        for (int j: i) cout<<j<<" ";
//        cout<<"\n";
//    }
    build(ans);
    return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:90:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   90 |         for (int j=0; j<v.size()-1; j++) {
      |                       ~^~~~~~~~~~~

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