Submission #984218

#	Time	Username	Problem	Language	Result	Execution time	Memory
984218		CSQ31	Toy Train (IOI17_train)	C++17	100 / 100	361 ms	1884 KiB

train

#include "train.h"
#include<bits/stdc++.h>
using namespace std;
#define sz(a) (int)(a.size())
const int MAXN = 5555;
vector<int>g[MAXN],gr[MAXN];
std::vector<int> who_wins(vector<int> a, vector<int> r, vector<int> u, vector<int> v) {
	int n = sz(a);
	vector<int>bwin(n,0);
	for(int i=0;i<sz(u);i++){
		g[u[i]].push_back(v[i]);
		gr[v[i]].push_back(u[i]);
	}
	function<void()>bfs = [&](){
		queue<int>q;
		vector<int>cnt(n,0),charge(n,0);
		for(int i=0;i<n;i++){
			if(r[i]){
				q.push(i);
				charge[i] = 1;
			}
			cnt[i] = sz(g[i]);
		}
		while(!q.empty()){
			int v = q.front();
			q.pop();
			for(int x:gr[v]){
				if(charge[x])continue;
				if(a[x]){
					charge[x] = 1;
					q.push(x);
				}else{
					cnt[x]--;
					if(cnt[x])continue;
					charge[x] = 1;
					q.push(x);
				}
			}
		}
		for(int i=0;i<n;i++){
			if(!charge[i]){
				q.push(i);
				bwin[i] = 1;
			}
		}
		for(int i=0;i<n;i++){
			if(r[i]){
				int cnt = 0;
				for(int x:g[i])cnt += bwin[x];
				if(a[i] && cnt == sz(g[i])){
					r[i] = 0;
					bwin[i] = 1;
				}
				if(!a[i] && cnt){
					r[i] = 0;
					bwin[i] = 1;
				}
			}
		}
	};
	while(true){
		int ncharge = 0;
		for(int i=0;i<n;i++)ncharge += r[i];
		bfs();
		for(int i=0;i<n;i++)ncharge -= r[i];
		if(!ncharge)break;
	}
	for(int i=0;i<n;i++)bwin[i] ^= 1;
	return bwin;
	
}

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