Submission #769688

#	Time	Username	Problem	Language	Result	Execution time	Memory
769688		SanguineChameleon	Split the Attractions (IOI19_split)	C++17	100 / 100	84 ms	19600 KiB

split

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

const int maxn = 1e5 + 20;
vector<int> adj[maxn];
int sz[maxn];
int par[maxn];
int high[maxn];
int depth[maxn];
bool flag[maxn];
int color[maxn];
int n, m, a, b, c;
pair<int, int> mi;
int cnt;

void dfs1(int u) {
	flag[u] = true;
	sz[u] = 1;
	high[u] = depth[u];
	for (auto v: adj[u]) {
		if (!flag[v]) {
			par[v] = u;
			depth[v] = depth[u] + 1;
			dfs1(v);
			sz[u] += sz[v];
			high[u] = min(high[u], high[v]);
		}
		else {
			high[u] = min(high[u], depth[v]);
		}
	}
	if (sz[u] >= a) {
		mi = min(mi, make_pair(sz[u], u));
	}
}

void dfs2(int u) {
	if (n - mi.first >= a) {
		return;
	}
	if (u != mi.second && high[u] < depth[mi.second]) {
		flag[u] = true;
		mi.first -= sz[u];
		return;
	}
	for (auto v: adj[u]) {
		if (par[v] == u) {
			dfs2(v);
		}
	}
}

void dfs3(int u) {
	if (cnt == a || flag[u]) {
		return;
	}
	color[u] = 1;
	cnt++;
	for (auto v: adj[u]) {
		if (par[v] == u) {
			dfs3(v);
		}
	}
}

vector<int> solve() {
	mi = make_pair(n + 1, -1);
	par[0] = -1;
	dfs1(0);
	for (int i = 0; i < n; i++) {
		flag[i] = false;
	}
	dfs2(mi.second);
	if (n - mi.first < a) {
		return vector<int>(n, 0);
	}
	bool flip = n - mi.first < b;
	if (flip) {
		swap(a, b);
	}
	dfs3(mi.second);
	for (int i = 0; i < n; i++) {
		flag[i] = false;
	}
	for (int i = 0; i < n; i++) {
		if (!color[i] && !flag[i]) {
			flag[i] = true;
			vector<int> comp;
			comp.push_back(i);
			int sz = 1;
			int pt = 0;
			while (pt < sz) {
				int u = comp[pt++];
				for (auto v: adj[u]) {
					if (!color[v] && !flag[v]) {
						flag[v] = true;
						comp.push_back(v);
						sz++;
					}
				}
			}
			if ((int)comp.size() >= b) {
				for (int j = 0; j < b; j++) {
					color[comp[j]] = 2;
				}
			}
		}
	}
	vector<int> res(n);
	for (int i = 0; i < n; i++) {
		res[i] = color[i] ? (color[i] ^ (flip ? 3 : 0)) : 3;
	}
	return res;
}

vector<int> find_split(int _n, int _a, int _b, int _c, vector<int> p, vector<int> q) {
	n = _n;
	m = p.size();
	for (int i = 0; i < m; i++) {
		adj[p[i]].push_back(q[i]);
		adj[q[i]].push_back(p[i]);
	}
	vector<pair<int, int>> order = {{_a, 1}, {_b, 2}, {_c, 3}};
	sort(order.begin(), order.end());
	a = order[0].first;
	b = order[1].first;
	c = order[2].first;
	vector<int> res = solve();
	for (int i = 0; i < n; i++) {
		if (res[i] > 0) {
			res[i] = order[res[i] - 1].second;
		}
	}
	return res;
}

• Subtask 1: 7 / 7
• Subtask 2: 11 / 11
• Subtask 3: 22 / 22
• Subtask 4: 24 / 24
• Subtask 5: 36 / 36