Submission #941888

#	Time	Username	Problem	Language	Result	Execution time	Memory
941888		Minbaev	One-Way Streets (CEOI17_oneway)	C++17	100 / 100	601 ms	88584 KiB

oneway

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define pii pair<int,int>
using namespace __gnu_pbds;
using namespace std;
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define f first
#define int long long
#define s second
#define pii pair<int,int>
template<class T>bool umax(T &a,T b){if(a<b){a=b;return true;}return false;}
template<class T>bool umin(T &a,T b){if(b<a){a=b;return true;}return false;}
typedef tree<int, null_type, less_equal<int>, rb_tree_tag,
	tree_order_statistics_node_update> ordered_set;
const int N=3e5 + 5	;
const int inf = 1e17 + 7;
const int mod = 998244353;

map<pii,int>e_cnt,edge,mp;

vector<int>g[N],vis(N),tin(N),fup(N),color(N),A(N),B(N),ans(N);

vector<pii>v[N],nw;

int n,m,k, timer;


void bridge(int x, int p = -1){

	vis[x] = 1;
	tin[x] = ++timer;
	fup[x] = ++timer;
	
	for(auto to:g[x]){
		if(to == p)continue;
		if(vis[to]){
			 umin(fup[x],fup[to]);
		}
		else{
			bridge(to,x);
			umin(fup[x],fup[to]);
			if(fup[to]>tin[x]){
				mp[{x,to}] = 1;
				mp[{to,x}] = 1;
			}
		}
	}
}

void dfs(int x, int col){
	
	vis[x] = 1;
	color[x] = col;
	
	for(auto to:g[x]){
		if(vis[to])continue;
		
		if(mp[{x,to}] != 1 || e_cnt[{to,x}] > 1)
			dfs(to,col);
	}
}

void DFS(int x, int p){
	vis[x] = 1;
	for(auto [to,ind]:v[x]){
		if(to == p)continue;
		DFS(to,x);
		A[x] += A[to];
		B[x] += B[to];
	}
	
	for(auto [to,ind]:v[x]){
		if(to == p) continue;
		if(A[to] != B[to]){
			
			if(ind < 0)
				ans[-ind]=1;
			else
				ans[ind]=0;
			if(B[to]>A[to]) ans[abs(ind )]^=1;
		}
	}
	
}
int c = 1;
void magic_nahuy(){
	
	int op;cin >> op;
	for(int i = 1;i<=m;i++){
		ans[i] = 2;
	}
	
	for(int i = 1;i<=n;i++){
		vis[i] = 0;
	}
	
	for(int i = 0;i<op;i++){
		int a,b;
		cin >> a >> b;
		A[color[a]] += 1;
		B[color[b]] += 1;
	}
	
	
	for(int i = 1;i<=c;i++){
		if(vis[i])continue;
			DFS(i,-1);
	}
	
	for(int i = 1;i<=m;i++){
		if(ans[i] == 2)cout<<"B";
		if(ans[i] == 1)cout<<"R";
		if(ans[i] == 0)cout<<"L";
		
		
	}
	
}

void solve(){
	
	cin >> n >> m;
	
	for(int i = 1; i<=m ;i++){
		int a,b;
		cin >> a >> b;
		
		e_cnt[{a,b}] += 1;
		e_cnt[{b,a}] += 1;
		
		g[a].pb(b);
		g[b].pb(a);
		
		edge[{a,b}] = i;
		edge[{b,a}] = -i;
		
		nw.pb({a,b});
	}
	
	
	
	for(int i = 1;i<=n;i++){
		if(vis[i])continue;
			bridge(i);
	}
	
	for(int i = 1;i<=n;i++){
		vis[i] = 0;
	}
	
	
	for(int i = 1;i<=n;i++){
		if(vis[i])continue;
			dfs(i,c++);
		
	}
	
	for(auto it:nw){
		if(color[it.f] == color[it.s])continue;
		
		v[color[it.f]].pb({color[it.s],edge[it]});
		v[color[it.s]].pb({color[it.f],-edge[it]});
	}
	
	magic_nahuy();
	
}

signed main()
{
//	freopen("seq.in", "r", stdin);
//  freopen("seq.out", "w", stdout);
	ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL);
	int tt=1;//cin>>tt>>n;
	while(tt--)solve();

}

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