Submission #1002655

#	Time	Username	Problem	Language	Result	Execution time	Memory
1002655		toast12	Connecting Supertrees (IOI20_supertrees)	C++14	11 / 100	117 ms	24164 KiB

supertrees

#include "supertrees.h"
#include <vector>
#include <map>
#include <iostream>
#include <set>
using namespace std;

#define sz(x) (int)x.size()

struct DSU {
	int n;
	vector<int> link, size;
	DSU(int sz) {
		n = sz;
		link.resize(sz);
		size.resize(sz);
		for (int i = 0; i < n; i++) {
			link[i] = i;
			size[i] = 1;
		}
	}
	int find(int x) {
		while (x != link[x])
			x = link[x];
		return x;
	} 
	bool same(int a, int b) {
		return find(a) == find(b);
	}
	void unite(int a, int b) {
		a = find(a);
		b = find(b);
		if (a == b)
			return;
		if (size[a] < size[b])
			swap(a, b);
		link[b] = a;
		size[a] += size[b];
	}
};

int construct(std::vector<vector<int>> p) {
	int n = p.size();
	vector<vector<int>> answer(n, vector<int>(n));
	vector<vector<int>> c(n);
	DSU d(n+1);
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			if (i == j)
				continue;
			if (p[i][j]) {
				if (!d.same(i, j)) {
					d.unite(i, j);
					int x = d.find(i);
					c[x].push_back(j);
					c[x].push_back(i);
				}
			}
		}
	}
	for (int i = 0; i < n; i++) {
		if (sz(c[i]) <= 1)
			continue;
		vector<bool> done(n);
		vector<int> x;
		for (int j = 0; j < sz(c[i]); j++) {
			if (!done[c[i][j]])
				x.push_back(c[i][j]);
			done[c[i][j]] = true;
		}
		vector<int> one, two;
		for (int j = 0; j < sz(x); j++) {
			int r = x[j];
			bool o = false;
			for (int k = 0; k < n; k++) {
				if (k == r)
					continue;
				if (p[r][k] == 1) {
					o = true;
					break;
				}
			}
			if (!o)
				two.push_back(x[j]);
			else
				one.push_back(x[j]);
		}
		DSU dsu(n+1);
		set<int> roots;
		if (!one.empty()) {
			for (auto o : one) {
				for (int j = 0; j < n; j++) {
					if (j == o)
						continue;
					if (p[o][j] == 1 && !dsu.same(o, j)) {
						answer[o][j] = 1;
						answer[j][o] = 1;
						dsu.unite(j, o);
						roots.insert(dsu.find(j));
					}
				}
			}
		}
		if (!two.empty()) {
			for (auto x : roots)
				two.push_back(x);
			for (int j = 0; j < sz(two)-1; j++) {
				answer[two[j]][two[j+1]] = 1;
				answer[two[j+1]][two[j]] = 1;
				dsu.unite(two[j], two[j+1]);
			}
			answer[two.back()][two[0]] = 1;
			answer[two[0]][two.back()] = 1;
		}
	}
	for (int i = 0; i < n; i++) {
		answer[i][i] = 0;
	}
	build(answer);
	return 1;
}

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