Submission #581609

#	Time	Username	Problem	Language	Result	Execution time	Memory
581609		Valaki2	Connecting Supertrees (IOI20_supertrees)	C++14	100 / 100	239 ms	24180 KiB

supertrees

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

#define pb push_back

int n;
vector<vector<int> > answer;

void add_edge(int x, int y) {
    answer[x][y] = 1;
    answer[y][x] = 1;
}

void dfs(int cur, vector<vector<int> > &p, int &comp_cnt, vector<int> &comp, vector<int> &poss, int weight, vector<vector<int> > &by_comp) {
    comp[cur] = comp_cnt;
    by_comp[comp_cnt - 1].pb(cur);
    for(int nei : poss) {
        if(!comp[nei] && p[cur][nei] == weight) {
           dfs(nei, p, comp_cnt, comp, poss, weight, by_comp);
        }
    }
}

int construct(vector<vector<int> > p) {
    n = (int) p.size();
    answer.assign(n, vector<int> (n, 0));
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < n; j++) {
            if(p[i][j] == 3) {
                return 0;
            }
        }
    }
    int tree_cnt = 0;
    vector<int> which_tree(n, 0);
    vector<int> all(n, 0);
    for(int i = 0; i < n; i++) {
        all[i] = i;
    }
    vector<vector<int> > by_tree(n, vector<int> (0, 0));
    for(int cur : all) {
        if(!which_tree[cur]) {
            tree_cnt++;
            dfs(cur, p, tree_cnt, which_tree, all, 1, by_tree);
        }
    }
    by_tree.resize(tree_cnt);
    vector<int> rep(n, -1);
    vector<int> list_reps;
    for(vector<int> &tree : by_tree) {
        list_reps.pb(tree[0]);
        for(int &cur : tree) {
            rep[cur] = tree[0];
        }
        for(int i = 0; i + 1 < (int) tree.size(); i++) {
            add_edge(tree[i], tree[i + 1]);
        }
        for(int x : tree) {
            for(int y : tree) {
                if(x != y && p[x][y] != 1) {
                    return 0;
                }
            }
        }
    }
    for(int x = 0; x < n; x++) {
        for(int y = 0; y < n; y++) {
            if(p[x][y] != p[rep[x]][rep[y]]) {
                return 0;
            }
        }
    }
    int cycle_cnt = 0;
    vector<int> which_cycle(n, 0);
    vector<vector<int> > by_cycle(n, vector<int> (0, 0));
    for(int cur : list_reps) {
        if(!which_cycle[cur]) {
            cycle_cnt++;
            dfs(cur, p, cycle_cnt, which_cycle, list_reps, 2, by_cycle);
        }
    }
    by_cycle.resize(cycle_cnt);
    for(vector<int> &cycle : by_cycle) {
        if((int) cycle.size() == 2) {
            return 0;
        }
        if((int) cycle.size() != 1) {
            for(int i = 0; i + 1 < (int) cycle.size(); i++) {
                add_edge(cycle[i], cycle[i + 1]);
            }
            add_edge(cycle.back(), cycle[0]);
        }
        for(int x : cycle) {
            for(int y : cycle) {
                if(x != y && p[x][y] != 2) {
                    return 0;
                }
            }
        }
    }
	build(answer);
	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