Submission #655843

#	Time	Username	Problem	Language	Result	Execution time	Memory
655843		manizare	One-Way Streets (CEOI17_oneway)	C++17	60 / 100	522 ms	262144 KiB

oneway

#include<bits/stdc++.h>
#define all(a) a.begin(),a.end()
#define pb push_back
using namespace std ;

const int maxn = 2e6 + 10 , maxq = 502 , inf = 1e9 , mod = 1e9+7 ;
vector <pair <int , int > > G[maxn] ;
vector <int>  l[maxn] ;
int dp[maxn] , mark2[maxn] , mark[maxn] , par[maxn]  , cnt = 1 ,c[maxn] , st[maxn] , en[maxn] , pr[maxn] , pp[maxn] , ans[maxn] , ok[maxn]; 
pair <int , int > ed[maxn] ;
void dfs(int v){ 
	mark[v] = 1;
	for(int i = 0; i < (int)G[v].size() ; i++){
		int u = G[v][i].first , id = G[v][i].second ;
		if(mark[u] == 1){
			if(mark2[id] == 0){
				dp[v] ++ ;
				dp[u] -- ;
				ans[id] = 3 ;
				mark2[id] = 1; 
			}
			continue ;
		}
		mark2[id] = 1;
		par[u] = id ;
		dfs(u) ;
		dp[v]+=dp[u];
	}
}

void dfs2(int v , int r){
	mark[v] = 1;
	c[v] = r ;
	for(int i = 0; i < (int)G[v].size() ; i++){
		int u = G[v][i].first , id = G[v][i].second ;
		if(mark[u] == 1)continue ;
		if(dp[u] == 0){
			cnt ++;
			//cout << v << " " << u << "<---\n";
			pr[cnt] = id ;
			pp[cnt] = r ;
			l[r].pb(cnt);
			dfs2(u , cnt);
		}else{
			dfs2(u , r);
		}
	}
}
vector <int> vv[maxn] , uu[maxn] ;
int sec = 1 ;
void dfs3(int v){
	mark[v] = 1;
	for(int i = 0 ;i < (int)l[v].size() ; i++){
		int u = l[v][i] ;
		dfs3(u);
	}
	if(pp[v] == 0)return ; 
	int ok = 0 ;
	vector <int> xx , yy ;
	sort(all(vv[v]));sort(all(uu[v]));
	while(vv[v].size() > 0 && uu[v].size() > 0){
		int vx = vv[v].back() , vz = uu[v].back() ;
		if(vx == vz){
			vv[v].pop_back();
			uu[v].pop_back();
		}else if(vx > vz){
			vv[pp[v]].pb(vx);
			xx.pb(vx);
			vv[v].pop_back();
		}else{
			yy.pb(vz);
			uu[pp[v]].pb(vz);
			uu[v].pop_back();
		}
	}
	while(vv[v].size() > 0){
		int vx = vv[v].back(); vv[v].pop_back();
		xx.pb(vx);
		vv[pp[v]].pb(vx);
	}
	while(uu[v].size() > 0){
		int vx = uu[v].back() ; uu[v].pop_back();
		yy.pb(vx);
		uu[pp[v]].pb(vx);
	}
	int id = pr[v]; 
	if(xx.size() == 0 && yy.size() ==0 ){
		ans[pr[v]] = 3 ;
	}else if (yy.size() == 0){
		if(c[ed[id].first] == v){
			ans[id] = 2 ; 
		}else{
			ans[id] = 1 ;
		}
	}else{
		if(c[ed[id].first] == v){
			ans[id] = 1 ;
		}else{
			ans[id] = 2 ;
		}
	}
	uu[v].clear();
	vv[v].clear();
}

signed main(){
	ios::sync_with_stdio(false); cin.tie(0);cout.tie(0);
	int n , m ;
	cin >> n >> m ;
	for(int i =1  ;i <= m ; i++){
		int v , u ;
		cin >> v >> u ;
		if(v==u){
			ans[i] = 3; 
			continue ;
		}
		G[v].pb({u,i});
		G[u].pb({v,i});
		ed[i] = {v , u} ;
	}
	for(int i = 1; i <= n ; i++){
		if(mark[i] == 1)continue ;
		dfs(i);
	}
	for(int i =1 ; i <= n ; i++){
		if(par[i] == 0)continue ;
		if(dp[i] >= 1){
			ans[par[i]] = 3 ;
		}
	}
	memset(mark , 0 , sizeof mark);
	memset(mark2 , 0 , sizeof mark2);
	vector <int> vec ;
	for(int i =1; i <= n ; i ++){
		if(mark[i] == 1)continue ;
		vec.pb(cnt);
		dfs2(i ,cnt ) ;
		cnt++;
	}
	memset(mark , 0 , sizeof mark);

	int q ;
	cin >> q ;
	while(q--){
		int v , u ;
		cin >> v >> u ;
		if(c[v] == c[u])continue ;
		vv[c[v]].pb(q);
		uu[c[u]].pb(q);
	}
	for(int i =0 ; i < (int)vec.size() ;i++){
		int u = vec[i]; 
		dfs3(u);
	}
	for(int i = 1 ; i <= m ; i++){
		if(ans[i] == 3){
			cout << "B";
		}
		if(ans[i] == 2){
			cout << "R";
		}
		if(ans[i] == 1){
			cout << "L" ;
		}
	}
	cout << endl;
}

Compilation message (stderr)

oneway.cpp: In function 'void dfs3(int)':
oneway.cpp:58:6: warning: unused variable 'ok' [-Wunused-variable]
   58 |  int ok = 0 ;
      |      ^~

• Subtask 1: 30 / 30
• Subtask 2: 30 / 30
• Subtask 3: 0 / 40