Submission #770827

#	Time	Username	Problem	Language	Result	Execution time	Memory
770827		SanguineChameleon	Connecting Supertrees (IOI20_supertrees)	C++17	100 / 100	187 ms	27996 KiB

supertrees

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

const int maxn = 1e3 + 20;
int cnt[maxn][maxn];
vector<vector<int>> res;
bool flag[maxn];
int n;

void add_edge(int u, int v) {
	res[u][v] = true;
	res[v][u] = true;
}

bool solve(vector<int> comp) {
	for (auto u: comp) {
		for (auto v: comp) {
			if (cnt[u][v] == 0) {
				return false;
			}
		}
	}
	for (auto i: comp) {
		flag[i] = false;
	}
	vector<vector<int>> chains;
	for (auto i: comp) {
		if (!flag[i]) {
			flag[i] = true;
			vector<int> chain = {i};
			int pt = 0;
			int sz = 1;
			while (pt < sz) {
				int u = chain[pt++];
				for (int v = 0; v < n; v++) {
					if (!flag[v] && cnt[u][v] == 1) {
						flag[v] = true;
						chain.push_back(v);
						sz++;
					} 
				}
			}
			for (auto u: chain) {
				for (auto v: chain) {
					if (cnt[u][v] != 1) {
						return false;
					}
				}
			}
			for (int i = 0; i < (int)chain.size() - 1; i++) {
				add_edge(chain[i], chain[i + 1]);
			}
			chains.push_back(chain);
		}
	}
	int sz = chains.size();
	if (sz == 2) {
		return false;
	}
	if (sz >= 3) {
		for (int i = 0; i < sz; i++) {
			add_edge(chains[i].back(), chains[(i + 1) % sz].back());
		}
	}
	return true;
}

int construct(vector<vector<int>> _cnt) {
	n = _cnt.size();
	res.resize(n, vector<int>(n, 0));
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			cnt[i][j] = _cnt[i][j];
			if (cnt[i][j] == 3) {
				return 0;
			}
		}
	}
	for (int i = 0; i < n; i++) {
		if (!flag[i]) {
			flag[i] = true;
			vector<int> comp = {i};
			int pt = 0;
			int sz = 1;
			while (pt < sz) {
				int u = comp[pt++];
				for (int v = 0; v < n; v++) {
					if (!flag[v] && cnt[u][v] > 0) {
						flag[v] = true;
						comp.push_back(v);
						sz++;
					} 
				}
			}
			if (!solve(comp)) {
				return 0;
			}
		}
	}
	build(res);
	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