제출 #939945

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
939945		smartmonky	One-Way Streets (CEOI17_oneway)	C++14	100 / 100	566 ms	70072 KiB

oneway

#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx,avx2,fma")
#include <bits/stdc++.h>

#define ff first
#define ss second
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()

using namespace std;

int pow(int a,int b,int m){int ans=1;while(b){if(b&1){ans=(ans*a)%m;}b>>=1;a=(a*a)%m;}return ans;}
int binpow(int a,int b){int ans=1;while(b){if(b&1){ans=(ans*a);}b>>=1;a=(a*a);}return ans;}
  
const int N = 1e5 + 10;


int low[N], h[N], depth[N];
vector <int> g[N];
vector <int> gc[N];
int lead[N];
int vis[N], par[N];
int tin[N], tout[N], up[N][25], used[N];
int timer;

map <pair <int,int>, int > brid, was;

void dfsc(int v){
	vis[v] = 1;
	for(auto to : g[v]){
		if(vis[to] == 0 && !brid.count({v, to})){
			lead[to] = lead[v];
			dfsc(to);
		}
	}
}

void dfs_lca(int v, int p = 1) {
	tin[v] = ++timer;
	par[v] = p;
	depth[v] = depth[p] + 1;
	up[v][0] = p;
	for (int i=1; i<=20; ++i)
		up[v][i] = up[up[v][i-1]][i-1];
	for (auto to : gc[v]) {
		if (to == p)continue;
		dfs_lca(to, v);
	}
	tout[v] = ++timer;
}

bool upper (int a, int b) {
	return tin[a] <= tin[b] && tout[a] >= tout[b];
}

int lca (int a, int b) {
	if (upper (a, b))  return a;
	if (upper (b, a))  return b;
	for (int i=20; i>=0; --i)
		if (! upper (up[a][i], b))
			a = up[a][i];
	return up[a][0];
}


void dfs_low(int v, int p){
    used[v] = true;
    tin[v] = low[v] = ++timer;
	
    for (auto u : g[v]){
        if (u == p) continue;
        if (used[u]){
            low[v] = min(low[v], tin[u]);
        }else{
            dfs_low(u, v);
            low[v] = min(low[v], low[u]);
            if (was[{v, u}] <=  1 && low[u] > tin[v]){
				brid[{v, u}] = 1;
				brid[{u, v}] = 1;
			}
        }
    }
}

main(){
	iostream::sync_with_stdio(false);  
    cin.tie(nullptr);
    cout.tie(nullptr);
    int n, m;
    cin >> n >> m;
    
    vector <pair <int,int> > road;
    for(int i = 0; i < m; i++){
		int a, b;
		cin >> a >> b;
		g[a].pb(b);
		g[b].pb(a);
		was[{a, b}]++;
		was[{b, a}]++;
		road.pb({a, b});
	}
    
    for(int i = 1;  i<= n; i++){
		if(!used[i])dfs_low(i, i);
	}
	
	for(int i = 1; i <= n; i++){
		if(lead[i] == 0){
			lead[i] = i;
			dfsc(i);
		}	
	}
	set <pair <int,int> > st;
	for(auto x : road){
		if(brid.count(x)){
			if(st.find(x) != st.end())return EXIT_FAILURE;
			st.insert(x);
			gc[lead[x.ff]].pb(lead[x.ss]);
			gc[lead[x.ss]].pb(lead[x.ff]);
		}
	}
	
	memset(used, 0, sizeof(used));
	for(int i = 1; i <= n; i++){
		if(par[i] == 0){
			dfs_lca(i, i);
		}
	}
	
	int p;
	cin >> p;
	map <pair <int,int>, int> mp;
	vector <pair <int, pair <int,int> > > l;
	while(p--){
		int a, b;
		cin >> a >> b;
		a = lead[a];	
		b = lead[b];
		if(a == b)continue;
		int lc = lca(a, b);
		l.pb({depth[lc], {a, b}});
	}
	sort(all(l));
	vector <int> d(n + 1, 0);
	int cnt = 0;
	for(auto x : l){
		int a = x.ss.ff, b = x.ss.ss;
		int lc = lca(a, b);
		while(a != lc && d[a] == 0){
			cnt++;
			d[a] = 1;
			mp[{lead[a], par[lead[a]]}] = 1;
			a = par[lead[a]];
		}
		while(b != lc && d[b] == 0){
			cnt++;
			d[b] = 1;
			mp[{par[lead[b]], lead[b]}] = 1;
			b = par[lead[b]];
		}
	}
	for(auto x : road){
		int f = x.ff, s = x.ss;
		f = lead[f];
		s = lead[s];
		if(mp.count({f, s})){
			cout << 'R';
		}else if(mp.count({s, f})){
			cout << 'L';
		}else
			cout << 'B';
	}
}

컴파일 시 표준 에러 (stderr) 메시지

oneway.cpp:86:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   86 | main(){
      | ^~~~

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