제출 #1324515

#제출 시각아이디문제언어결과실행 시간메모리
1324515kasamchiConnecting Supertrees (IOI20_supertrees)C++20
100 / 100
107 ms26180 KiB
#include "supertrees.h"
#include <bits/stdc++.h>
using namespace std;

int construct(vector<vector<int>> p) {
	int n = p.size();

	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			if (p[i][j] == 3) {
				return 0;
			}
		}
	}

	vector<int> grp(n);
	for (int i = 0; i < n; i++) {
		grp[i] = i;
	}

	auto fnd = [&] (auto &&self, int a) {
		if (grp[a] == a) {
			return a;
		} else {
			return grp[a] = self(self, grp[a]);
		}
	};

	vector<vector<int>> edge(n, vector(n, 0));
	for (int i = 0; i < n; i++) {
		for (int j = i + 1; j < n; j++) {
			if (p[i][j] == 1) {
				int x = fnd(fnd, i), y = fnd(fnd, j);
				if (x != y) {
					edge[i][j] = edge[j][i] = 1;
					grp[x] = y;
				}
			}
		}
	}

	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			if (p[i][j] == 0 && fnd(fnd, i) == fnd(fnd, j)) {
				return 0;
			}
		}
	}

	vector<vector<int>> gvx(n);
	for (int i = 0; i < n; i++) {
		gvx[fnd(fnd, i)].push_back(i);
	}
	sort(gvx.begin(), gvx.end(), [] (vector<int> a, vector<int> b) {
		if (a.empty()) {
			return false;
		} else if (b.empty()) {
			return true;
		} else {
			return a[0] < b[0];
		}
	});
	while (gvx.back().empty()) {
		gvx.pop_back();
	}
	for (int i = 0; i < (int)gvx.size(); i++) {
		for (int u : gvx[i]) {
			grp[u] = i;
			if (p[u] != p[gvx[i][0]]) {
				return 0;
			}
		}
	}

	int m = gvx.size();
	vector<vector<int>> q(m, vector(m, 0));
	for (int i = 0; i < m; i++) {
		for (int j = 0; j < m; j++) {
			if (i == j) {
				q[i][j] = 1;
			} else {
				q[i][j] = p[gvx[i][0]][gvx[j][0]];
			}
		}
	}

	grp.clear(), grp.resize(m);
	for (int i = 0; i < m; i++) {
		grp[i] = i;
	}
	for (int i = 0; i < m; i++) {
		for (int j = i + 1; j < m; j++) {
			if (q[i][j] == 2) {
				int x = fnd(fnd, i), y = fnd(fnd, j);
				grp[x] = y;
			}
		}
	}

	vector<bool> vis(m);
	for (int i = 0; i < m; i++) {
		if (!vis[i]) {
			vector<int> cyc = {i};
			vis[i] = true;
			for (int j = i + 1; j < m; j++) {
				int x = fnd(fnd, i), y = fnd(fnd, j);
				if (x == y) {
					cyc.push_back(j);
					vis[j] = true;
				}
			}
			if (cyc.size() == 1) {
				continue;
			}
			if (cyc.size() == 2) {
				return 0;
			}
			for (int u : cyc) {
				for (int v : cyc) {
					if (u != v && q[u][v] != 2) {
						return 0;
					}
				}
			}
			for (int i = 1; i < (int)cyc.size(); i++) {
				int u = gvx[cyc[i]][0], v = gvx[cyc[i - 1]][0];
				edge[u][v] = edge[v][u] = 1;
			}
			int u = gvx[cyc[0]][0], v = gvx[cyc.back()][0];
			edge[u][v] = edge[v][u] = 1;
		}
	}

	build(edge);
	return 1;
}
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