oj.uz

Submission #939760

# Submission time Handle Problem Language Result Execution time Memory
939760 2024-03-06T17:43:59 Z vjudge1 One-Way Streets (CEOI17_oneway) C++17
60 / 100
 3000 ms 62428 KB 
#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);
		while(a != lc){
			//cout << "--"<<a << endl;
			//if(par[a] == 0)return EXIT_FAILURE;
			mp[{lead[a], par[lead[a]]}] = 1;
			a = par[lead[a]];
		}
		while(b != lc){
			//if(par[b] == 0)return EXIT_FAILURE;
			mp[{par[lead[b]], lead[b]}] = 1;
			b = par[lead[b]];
		}
		l.pb({depth[lc], {a, b}});
	}
	sort(all(l));
	vector <int> d(n + 1, 0);
	for(auto x : l){
		int a = x.ss.ff, b = x.ss.ss;
		a = lead[a];	
		b = lead[b];
		if(a == b)continue;
		int lc = lca(a, b);
		while(a != lc && !d[a]){
			d[a] = 1;
			mp[{lead[a], par[lead[a]]}] = 1;
			a = par[lead[a]];
		}
		while(b != lc && !d[b]){
			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';
	}
}

Compilation message

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

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 11096 KB Output is correct
2 Correct 2 ms 11096 KB Output is correct
3 Correct 3 ms 11356 KB Output is correct
4 Correct 4 ms 11364 KB Output is correct
5 Correct 5 ms 11612 KB Output is correct
6 Correct 3 ms 11100 KB Output is correct
7 Correct 5 ms 11616 KB Output is correct
8 Correct 4 ms 11352 KB Output is correct
9 Correct 3 ms 11100 KB Output is correct
10 Correct 3 ms 11100 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 11096 KB Output is correct
2 Correct 2 ms 11096 KB Output is correct
3 Correct 3 ms 11356 KB Output is correct
4 Correct 4 ms 11364 KB Output is correct
5 Correct 5 ms 11612 KB Output is correct
6 Correct 3 ms 11100 KB Output is correct
7 Correct 5 ms 11616 KB Output is correct
8 Correct 4 ms 11352 KB Output is correct
9 Correct 3 ms 11100 KB Output is correct
10 Correct 3 ms 11100 KB Output is correct
11 Correct 136 ms 28344 KB Output is correct
12 Correct 136 ms 31464 KB Output is correct
13 Correct 174 ms 35652 KB Output is correct
14 Correct 298 ms 41936 KB Output is correct
15 Correct 297 ms 43728 KB Output is correct
16 Correct 438 ms 55512 KB Output is correct
17 Correct 685 ms 60568 KB Output is correct
18 Correct 403 ms 55616 KB Output is correct
19 Correct 653 ms 62428 KB Output is correct
20 Correct 147 ms 32964 KB Output is correct
21 Correct 125 ms 32400 KB Output is correct

Subtask #3
0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 11096 KB Output is correct
2 Correct 2 ms 11096 KB Output is correct
3 Correct 3 ms 11356 KB Output is correct
4 Correct 4 ms 11364 KB Output is correct
5 Correct 5 ms 11612 KB Output is correct
6 Correct 3 ms 11100 KB Output is correct
7 Correct 5 ms 11616 KB Output is correct
8 Correct 4 ms 11352 KB Output is correct
9 Correct 3 ms 11100 KB Output is correct
10 Correct 3 ms 11100 KB Output is correct
11 Correct 136 ms 28344 KB Output is correct
12 Correct 136 ms 31464 KB Output is correct
13 Correct 174 ms 35652 KB Output is correct
14 Correct 298 ms 41936 KB Output is correct
15 Correct 297 ms 43728 KB Output is correct
16 Correct 438 ms 55512 KB Output is correct
17 Correct 685 ms 60568 KB Output is correct
18 Correct 403 ms 55616 KB Output is correct
19 Correct 653 ms 62428 KB Output is correct
20 Correct 147 ms 32964 KB Output is correct
21 Correct 125 ms 32400 KB Output is correct
22 Execution timed out 3034 ms 60444 KB Time limit exceeded
23 Halted 0 ms 0 KB -