제출 #161568

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
161568		shayan_p	One-Way Streets (CEOI17_oneway)	C++14	0 / 100	11 ms	10236 KiB

oneway

// Remember...

#include<bits/stdc++.h>

#define F first
#define S second
#define PB push_back
#define sz(s) int((s).size())
#define bit(n,k) (((n)>>(k))&1)

using namespace std;

typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

const int maxn=1e5+10,mod=1e9+7;
const ll inf=1e18;

vector<pii> v[maxn], g[maxn];
int C, h[maxn], hh[maxn];
bool mark[maxn];

int ans[maxn], who[maxn];

void prep(int u,int par=-1){
    mark[u]=1;
    hh[u]= h[u];
    for(auto p:v[u]){
	if(p.S!=par){
	    if(mark[p.F])
		hh[u]=min(hh[u], h[p.F]);
	    else
		h[p.F]= h[u]+1, prep(p.F,p.S), hh[u]=min(hh[u], hh[p.F]);
	}
    }
}
void buildg(int u,int id){
    who[u]=id;
    mark[u]=1;
    for(auto p:v[u]){
	if(mark[p.F]==0){
	    if(hh[p.F]==h[p.F])
		g[id].PB({++C,p.S}), buildg(p.F,C);
	    else
		buildg(p.F,id);
	}
    }
}

map<int,bool> mp[maxn];

void dfs(int u,int par=-1){
    for(auto p:g[u]){
	if(p.S!=par){
	    dfs(p.F,p.S);
	    if(sz(mp[u]) < sz(mp[p.F])) swap(mp[u],mp[p.F]);
	    for(auto pp:mp[p.F]){
		if(mp[u].count(pp.F))
		    mp[u].erase(pp.F);
		else
		    mp[u][pp.F]=pp.S;
	    }
	    mp[p.F].clear();
	}
    }
    if(!mp[u].empty() &&  (mp[u].begin()->S))
	ans[par]=1;
    if(!mp[u].empty() && !(mp[u].begin()->S))
	ans[par]=0;
}

vector<pii> ed;

int main(){
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie();

    memset(ans,-1,sizeof ans);
    
    int n,m; cin>>n>>m;

    for(int i=0;i<m;i++){
	int a,b; cin>>a>>b;
	v[a].PB({b,i});
	v[b].PB({a,i});
	ed.PB({a,b});
    }
    prep(1);
    memset(mark,0,sizeof mark);
    buildg(1,++C);

    int q; cin>>q;
    for(int i=0;i<q;i++){
	int a,b; cin>>a>>b;
	a=who[a], b=who[b];
	if(a!=b){
	    mp[a][i]=1, mp[b][i]=0;
	}
    }
	
    dfs(1);

    for(int i=0;i<m;i++){
	if(ans[i]==-1) cout<<'B';
	else if((ans[i]) ^ (h[ed[i].F] > h[ed[i].S])) cout<<'L';
	else cout<<'R';
    }
    return cout<<endl,0;
}
// Deathly mistakes:
//  * Read the problem carefully.
//  * Check maxn.
//  * Overflows.


// #pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

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