Submission #724298

#	Time	Username	Problem	Language	Result	Execution time	Memory
724298		QwertyPi	Split the Attractions (IOI19_split)	C++14	100 / 100	127 ms	29348 KiB

split

#include "split.h"
#include <bits/stdc++.h>
using namespace std;
 
const int N = 2e5 + 11;
vector<int> G[N], sons[N];
bool vis[N]; int pa[N]; int sz[N];
int st[N], low[N], t = 0;
void dfs(int v){
	vis[v] = true; low[v] = st[v] = ++t;
	for(auto i : G[v]){
		if(!vis[i]){
			dfs(i); pa[i] = v; sons[v].push_back(i);
			low[v] = min(low[i], low[v]);
		}else{
			low[v] = min(st[i], low[v]);
		}
	}
}
 
void dfs2(int v){
	sz[v] = 1;
	for(auto i : sons[v]){
		dfs2(i); sz[v] += sz[i];
	}
}
 
vector<int> res;
int cur_sz = 0;
set<int> ban;
void bfs(int v, int par, int fil){
	if(cur_sz == 0 || ban.count(v)) return;
	res[v] = fil; cur_sz--;
	for(auto i : sons[v]){
		bfs(i, v, fil);
	}
}
void bfs2(int v, int par, int fil){
	if(cur_sz == 0) return;
	res[v] = fil; cur_sz--;
	for(auto i : G[v]){
		if(i != par && !res[i]) bfs2(i, v, fil);
	}
}
 
vector<int> find_split(int n, int a, int b, int c, vector<int> p, vector<int> q) {
	for(int i = 0; i < p.size(); i++){
		G[p[i]].push_back(q[i]);
		G[q[i]].push_back(p[i]);
	}
	dfs(0);
	dfs2(0);
	int v1 = 1, v2 = 2, v3 = 3;
	if(a > b) swap(a, b), swap(v1, v2);
	if(b > c) swap(b, c), swap(v2, v3);
	if(a > b) swap(a, b), swap(v1, v2);
	if(b > c) swap(b, c), swap(v2, v3);
	res.resize(n);
	for(int i = 0; i < n; i++){
		if(sz[i] >= a && sz[i] <= n - a){
			if(sz[i] <= n / 2){   
				cur_sz = a; bfs(i, pa[i], v1);
				cur_sz = b; bfs2(pa[i], -1, v2);
				for(auto& i : res) if(i == 0) i = v3;
			}else{
				cur_sz = b; bfs(i, pa[i], v2);
				cur_sz = a; bfs2(pa[i], -1, v1);
				for(auto& i : res) if(i == 0) i = v3;
			}
			return res;
		}
		bool ok = true;
		ok &= sz[i] > n - a;
		for(auto j : sons[i]){
			ok &= sz[j] < a;
		}
		if(ok){
			int D = i, now_sz = sz[i];
			for(auto j : sons[D]){
				if(now_sz > n - a && low[j] < st[D]){
					now_sz -= sz[j]; ban.insert(j);
				}
			}
			if(now_sz <= n - a){
				cur_sz = b; bfs(D, pa[D], v2);
				cur_sz = a; bfs2(pa[D], -1, v1);
				for(auto& i : res) if(i == 0) i = v3;
				return res;
			}
		}
	}
	return res;
}

Compilation message (stderr)

split.cpp: In function 'std::vector<int> find_split(int, int, int, int, std::vector<int>, std::vector<int>)':
split.cpp:47:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   47 |  for(int i = 0; i < p.size(); i++){
      |                 ~~^~~~~~~~~~

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