Submission #167782

#TimeUsernameProblemLanguageResultExecution timeMemory
167782oolimrySplit the Attractions (IOI19_split)C++14
18 / 100
174 ms25848 KiB
#include "split.h"
#include <bits/stdc++.h>

using namespace std;

typedef vector<int> vi;
typedef pair<int,int> ii;

static vi answer;
static vi adj[100005];
static vi child[100005];
static vi tree[100005];
static int sz[100005];
static int p[100005];
static bool vis[100005];

void dfs(int u){
	vis[u] = true;
	sz[u] = 1;
	for(int v : adj[u]){
		if(!vis[v]){
			child[u].push_back(v);
			tree[u].push_back(v);
			tree[v].push_back(u);
			p[v] = u;
			dfs(v);
			sz[u] += sz[v];
		}	
	}
}

void bfs(int root, int number){
	if(number == 0) return;
	queue<int> bf;
	bf.push(root);
	while(!bf.empty()){
		int u = bf.front(); bf.pop();
		for(int v : tree[u]){
			if(answer[v] == 0){
				answer[v] = answer[u];
				number--;
				if(number == 0) return;
				bf.push(v);
			}
		}
	}
}
vi find_split(int n, int aaa, int bbb, int ccc, vi p, vi q) {
	vector<ii> v = {ii(aaa,1),ii(bbb,2),ii(ccc,3)};
	sort(v.begin(),v.end());
	int A = v[0].first;
	int B = v[1].first;
	int AColour = v[0].second;
	int BColour = v[1].second;
	int CColour = v[2].second;
	
	answer.assign(n,0);
	
	for(int i = 0;i < (int) p.size();i++){
		int x = p[i], y = q[i];
		adj[y].push_back(x);
		adj[x].push_back(y);
	}
	
	dfs(0);
	
	for(int u = 0;u < n;u++){
		vector<ii> subtrees;
		for(int v : child[u]){
			subtrees.push_back({sz[v],v});
		}
		subtrees.push_back({n - sz[u],p[u]});
		
		for(ii x : subtrees){
			if(x.first >= A && n - x.first >= B){
				//cout << x.second << " " << u << "\n";
				answer[x.second] = AColour;
				answer[u] = BColour;
				bfs(x.second, A-1);
				bfs(u,B-1);
				for(int i = 0;i < n;i++){
					if(answer[i] == 0) answer[i] = CColour;
				}
				return answer;
			}
		}
	}
	
	return answer;
}
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