oj.uz

Submission #939759

# Submission time Handle Problem Language Result Execution time Memory
939759 2024-03-06T17:43:46 Z vjudge1 One-Way Streets (CEOI17_oneway) C++17
60 / 100
 3000 ms 62476 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(rall(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 4 ms 11100 KB Output is correct
3 Correct 4 ms 11356 KB Output is correct
4 Correct 4 ms 11356 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 11356 KB Output is correct
8 Correct 4 ms 11356 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 4 ms 11100 KB Output is correct
3 Correct 4 ms 11356 KB Output is correct
4 Correct 4 ms 11356 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 11356 KB Output is correct
8 Correct 4 ms 11356 KB Output is correct
9 Correct 3 ms 11100 KB Output is correct
10 Correct 3 ms 11100 KB Output is correct
11 Correct 115 ms 28380 KB Output is correct
12 Correct 142 ms 31688 KB Output is correct
13 Correct 209 ms 35780 KB Output is correct
14 Correct 242 ms 42132 KB Output is correct
15 Correct 285 ms 43568 KB Output is correct
16 Correct 401 ms 55440 KB Output is correct
17 Correct 671 ms 60616 KB Output is correct
18 Correct 424 ms 55592 KB Output is correct
19 Correct 714 ms 62476 KB Output is correct
20 Correct 149 ms 33156 KB Output is correct
21 Correct 136 ms 32596 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 4 ms 11100 KB Output is correct
3 Correct 4 ms 11356 KB Output is correct
4 Correct 4 ms 11356 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 11356 KB Output is correct
8 Correct 4 ms 11356 KB Output is correct
9 Correct 3 ms 11100 KB Output is correct
10 Correct 3 ms 11100 KB Output is correct
11 Correct 115 ms 28380 KB Output is correct
12 Correct 142 ms 31688 KB Output is correct
13 Correct 209 ms 35780 KB Output is correct
14 Correct 242 ms 42132 KB Output is correct
15 Correct 285 ms 43568 KB Output is correct
16 Correct 401 ms 55440 KB Output is correct
17 Correct 671 ms 60616 KB Output is correct
18 Correct 424 ms 55592 KB Output is correct
19 Correct 714 ms 62476 KB Output is correct
20 Correct 149 ms 33156 KB Output is correct
21 Correct 136 ms 32596 KB Output is correct
22 Execution timed out 3069 ms 60652 KB Time limit exceeded
23 Halted 0 ms 0 KB -