Submission #45483

#	Time	Username	Problem	Language	Result	Execution time	Memory
45483		Abelyan	Toy Train (IOI17_train)	C++14	0 / 100	16 ms	1776 KiB

train

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

const int N = 5006;
int n, m;
vector<int> g[N],ing[N];
bool col[N],chrg[N];
unordered_set <int> R;

unordered_set<int> rev(unordered_set<int> &s){
	unordered_set<int> ans;
	for (int i = 0; i < n; i++){
		if (s.count(i) == 0) ans.insert(i);
	}
	return ans;
}
unordered_set<int> fa(unordered_set<int> &s){
	unordered_set<int> ans;
	queue<int> q;
	for (auto k : s){
		q.push(k);
		ans.insert(k);
	}
	while (!q.empty()){
		int v = q.front();
		q.pop();
		for (auto to : ing[v]){
			if (ans.count(to)) continue;
			bool mb = true;
			for (auto k : g[to]){
				mb &= ans.count(k) == 1;
			}
			if (col[to] || mb){
				ans.insert(to);
				q.push(to);
			}
		}
	}
	return ans;
}

unordered_set<int> fb(unordered_set<int> &s){
	unordered_set<int> ans;
	queue<int> q;
	for (auto k : s){
		q.push(k);
		ans.insert(k);
	}
	while (!q.empty()){
		int v = q.front();
		q.pop();
		for (auto to : ing[v]){
			if (ans.count(to)==1) continue;
			bool mb = true;
			for (auto k : g[to]){
				mb &= ans.count(k) == 1;
			}
			if (!col[to] || mb){
				ans.insert(to);
				q.push(to);
			}
		}
	}
	return ans;
}

unordered_set<int> intersect(unordered_set<int> &a, unordered_set<int> &b){
	unordered_set<int> ans;
	for (auto i : a){
		if (b.count(i)) ans.insert(i);
	}
	return ans;
}

vector<int> who_wins(vector<int> a, vector<int> r, vector<int> u, vector<int> v) {
	n = a.size();
	m = u.size();
	for (int i = 0; i < m; i++){
		g[u[i]].push_back(v[i]);
		ing[v[i]].push_back(u[i]);
	}
	for (int i = 0; i < n; i++){
		if (a[i]){
			col[i] = true;
		}
	}
	for (int i = 0; i < n; i++){
		if (r[i]) chrg[i] = true;
	}
	while (1){
		for (int i = 0; i < n; i++){
			if (chrg[i]) R.insert(i);
		}
		unordered_set <int>  far = fa(R),gg=rev(far),x = fb(gg), ht = intersect(far, x);
		bool mb = false;
		for (auto k : ht){
			if (chrg[k]) mb = true, chrg[k] = false;
		}
		if (!mb){
			vector<int> ans(n);
			for (auto k : x){
				ans[k] = 1;
			}
			return ans;
		}
	}
}
/*
2 4 
0 1 
1 0 
0 0 
0 1 
1 0 
1 1 

*/

• Subtask 1: 0 / 5
• Subtask 2: 0 / 10
• Subtask 3: 0 / 11
• Subtask 4: 0 / 11
• Subtask 5: 0 / 12
• Subtask 6: 0 / 51