Submission #476355

#	Time	Username	Problem	Language	Result	Execution time	Memory
476355		cgiosy	One-Way Streets (CEOI17_oneway)	C++17	100 / 100	64 ms	11588 KiB

oneway

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

int main() {
	ios::sync_with_stdio(0);cin.tie(0);
	int N, M, Q;
	cin>>N>>M;
	int E[M*2+2], F[M*2+2], G[N]{};
	for(int i=1; i<=M; i++) {
		int a, b;
		cin>>a>>b; --a, --b;
		E[i*2]=b, F[i*2]=G[a], G[a]=i*2;
		E[i*2+1]=a, F[i*2+1]=G[b], G[b]=i*2+1;
	}

	int A[N]{}, T[N], P[N], t=0;
	char V[max(N, M)+1]{};
	function<int(int)> root=[&](int i) {
		return P[i]>=0 ? P[i]=root(P[i]) : i;
	};
	auto up=[&](int&i) { i=P[i]=root(~P[i]); };
	function<void(int, int)> bcc=[&](int i, int p) {
		A[i]=T[i]=++t;
		for(int e=G[i]; e; e=F[e]) if(e!=p) {
			int&j=E[e];
			if(A[j]) { T[i]=min(T[i], A[j]); continue; }
			V[e>>1]=e&1, P[j]=~i;
			bcc(j, e^1);
			T[i]=min(T[i], T[j]);
			if(A[i]<T[j]) V[e>>1]|=2;
		}
	};
	for(int i=0; i<N; i++) if(!A[i]) P[i]=~i, bcc(i, 0);

	cin>>Q;
	while(Q--) {
		int i, j, a=4, b=8;
		cin>>i>>j; --i, --j;
		if(A[i]<A[j]) swap(i, j), swap(a, b);
		for(i=root(i); A[i]>A[j]; up(i)) V[i]|=a;
		for(j=root(j); A[j]>A[i]; up(j)) V[j]|=b;
	}

	for(int i=1; i<=M; i++) {
		int v=V[i], u=v&1, t=V[E[i*2^u]]>>2;
		cout<<((v&2) && t ? (t^u)&1 ? 'L' : 'R' : 'B');
	}
}

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