Submission #832226

#	Time	Username	Problem	Language	Result	Execution time	Memory
832226		tranxuanbach	Split the Attractions (IOI19_split)	C++17	18 / 100	585 ms	1048576 KiB

split

#include "split.h"

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

#define isz(a) ((signed)a.size())

const int N = 1e5 + 5, M = 2e5 + 5;

int n, m;
vector <pair <int, int>> vcolor;
vector <int> adj[N];

vector <int> ans;

namespace subtask12{
	bool check(){
		for (auto &[cnt, col]: vcolor){
			if (col == 1 and cnt == 1){
				return true;
			}
		}
		for (int u = 0; u < n; u++){
			if (isz(adj[u]) > 2){
				return false;
			}
		}
		return true;
	}

	vector <bool> chosen;

	void dfs(int u){
		chosen[u] = true;
		ans[u] = vcolor.back().second;
		vcolor.back().first--;
		if (vcolor.back().first == 0){
			vcolor.pop_back();
		}
		for (auto v: adj[u]){
			if (chosen[v]){
				continue;
			}
			dfs(v);
		}
	}

	vector <int> solve(){
		chosen.assign(n, false);

		int s = 0;
		for (int u = 1; u < n; u++){
			if (isz(adj[u]) == 1){
				s = u;
				break;
			}
		}
		dfs(s);
		return ans;
	}
}

namespace subtask3{
	bool check(){
		return m == n - 1;
	}

	int sz[N];

	void dfs_sz(int u, int p = -1){
		sz[u] = 1;
		for (auto v: adj[u]){
			if (v == p){
				continue;
			}
			dfs_sz(v, u);
			sz[u] += sz[v];
		}
	}

	bool dfs_color(int u, int p, int cnt, int col){
		ans[u] = col;
		cnt--;
		if (cnt == 0){
			return true;
		}
		for (auto v: adj[u]){
			if (v == p){
				continue;
			}
			if (dfs_color(v, u, cnt, col)){
				return true;
			}
		}
		return false;
	}

	vector <int> solve(){
		dfs_sz(0);
		for (int u = 0; u < n; u++){
			for (auto v: adj[u]){
				if (sz[u] > sz[v]){
					continue;
				}
				if (sz[u] >= vcolor[0].first and n - sz[u] >= vcolor[1].first){
					fill(ans.begin(), ans.end(), vcolor[2].second);
					dfs_color(u, v, vcolor[0].first, vcolor[0].second);
					dfs_color(v, u, vcolor[1].first, vcolor[1].second);
					return ans;
				}
			}
		}
		return ans;
	}
}

vector <int> find_split(int _n, int a, int b, int c, vector <int> _u, vector <int> _v){
	n = _n; m = isz(_u);
	vcolor = {{a, 1}, {b, 2}, {c, 3}};
	sort(vcolor.begin(), vcolor.end());
	for (int i = 0; i < m; i++){
		int u = _u[i], v = _v[i];
		adj[u].emplace_back(v);
		adj[v].emplace_back(u);
	}
	ans.assign(n, 0);

	if (subtask12::check()){
		return subtask12::solve();
	}
	if (subtask3::check()){
		return subtask3::solve();
	}
}

Compilation message (stderr)

split.cpp: In function 'std::vector<int> find_split(int, int, int, int, std::vector<int>, std::vector<int>)':
split.cpp:134:1: warning: control reaches end of non-void function [-Wreturn-type]
  134 | }
      | ^

• Subtask 1: 7 / 7
• Subtask 2: 11 / 11
• Subtask 3: 0 / 22
• Subtask 4: 0 / 24
• Subtask 5: 0 / 36