oj.uz

Submission #1025775

# Submission time Handle Problem Language Result Execution time Memory
1025775 2024-07-17T09:53:14 Z Taxiradio One-Way Streets (CEOI17_oneway) C++17
100 / 100
 237 ms 37820 KB 
// Source: https://usaco.guide/general/io

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

vector<array<int , 2>> es;
vector<vector<array<int , 2>>> g1;
vector<int> comp , l, ti;
stack<int> u;
int t = 1 , c = 0; 

void dfs(int p , int b){
	l[p] = ti[p] = t++;
	u.push(p);
	for(auto [x , i]: g1[p]){
		if(b == i)continue;
		if(ti[x] == 0){
			dfs(x , i);
			if(l[x] > ti[p]){
				while(true){
					comp[u.top()] = c;
					if(u.top() == x){
						u.pop();
						break;
					}
					u.pop();
				}
				c++;
			}
			l[p] = min(l[p] , l[x]);
			continue;
		}
		l[p] = min(l[p] , ti[x]);
	}
}

vector<vector<array<int , 2>>> g2;
vector<bool> vis;

void dfs(int p){
	vis[p] = 1;
	for(auto [x , i]: g1[p]){
		if(vis[x])continue;
		if(comp[x] != comp[p]){
			g2[comp[x]].push_back({comp[p] , i});
			g2[comp[p]].push_back({comp[x] , i});
			//cout << comp[x] << " " << comp[p] << endl;
		}
		dfs(x);
	}
}

vector<array<int , 28>> bl;
vector<int> f;
vector<array<int , 2>> k;
void bls(int p , int e , int y){
	bl[p][0] = e;
	//cout << p << " " << e << endl;
	if(e==-1)f[p] = 0;else f[p] = f[e]+1;
	k[p][0] = e;
	k[p][1] = y;
	for(int i = 1; i < 28; i++){
		if(bl[p][i-1] == -1){
			bl[p][i] = -1;
			continue;
		}
		bl[p][i] = bl[bl[p][i-1]][i-1];
	}
	for(auto [x, i] : g2[p]){
		if(x==e)continue;
		bls(x , p , i);
	}
}

int get(int a , int b){
	if(f[a] < f[b])swap(a , b);
	for(int i = 27; i >=0; i--){
		if((1<<i) <= f[a]-f[b])a = bl[a][i];
	}
	if(a==b)return a;
	for(int i = 27; i >=0; i--){
		if(bl[a][i] != bl[b][i]){
			a = bl[a][i];
			b = bl[b][i];
		}
	}
	return bl[a][0];
}
vector<array<int , 3>> v;
vector<int> ans;
void solve(int i){
	//cout << v[i][0] << " " << v[i][1] << " " << v[i][2] << endl;
	int a = v[i][1];
	while(f[a] != v[i][0]){
		if(ans[k[a][1]] != 0)break;
		//cout << a << " " << k[a][0] << " " << k[a][1] << endl;
		if(comp[es[k[a][1]][0]] == a){
			ans[k[a][1]] = v[i][2];
		}else{
			ans[k[a][1]] = v[i][2]*-1;
		}
		a = k[a][0];
	}
}

int main() {
	int n , m; cin >> n >> m;
	g1.resize(n);
	comp.resize(n);
	l.resize(n);
	ti.resize(n);
	for(int i = 0; i < m; i++){
		int a , b; cin >> a >> b;
		g1[a-1].push_back({b-1 , i});
		g1[b-1].push_back({a-1 , i});
		es.push_back({a-1 , b-1});
	}
	vis.resize(n , false);
	g2.resize(n);
	bl.resize(n);
	k.resize(n);
	f.resize(n);
	for(int i = 0; i < n; i++){
		if(ti[i] == 0){
			dfs(i , -1);
			while(!u.empty()){
				comp[u.top()] = c;
				u.pop();
			}
			c++;
			dfs(i);
			bls(comp[i] , -1 , -1);
		}
	}
	/*
	for(int i = 0; i < n; i++){
		cout << comp[i] << " ";
	}
	*/
	int q; cin >> q;
	for(int i = 0; i < q; i++){
		int a , b; cin >> a >> b;
		a--;
		b--;
		int d = get(comp[a] , comp[b]);
		v.push_back({f[d] , comp[a] , -1});
		v.push_back({f[d] , comp[b] , 1});
	}
	sort(v.begin() , v.end());
	ans.resize(m, 0);
	for(int i = 0; i < v.size(); i++){
		solve(i);
	}
	//cout << "a "<<endl;
	for(int x : ans){
		if(x == 0)cout << "B";
		if(x == 1)cout << "L";
		if(x == -1)cout << "R";
	}
	cout << endl;
}

Compilation message

oneway.cpp: In function 'int main()':
oneway.cpp:151:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::array<int, 3> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  151 |  for(int i = 0; i < v.size(); i++){
      |                 ~~^~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 1 ms 604 KB Output is correct
4 Correct 1 ms 604 KB Output is correct
5 Correct 1 ms 604 KB Output is correct
6 Correct 1 ms 604 KB Output is correct
7 Correct 1 ms 604 KB Output is correct
8 Correct 1 ms 604 KB Output is correct
9 Correct 1 ms 348 KB Output is correct
10 Correct 1 ms 348 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 1 ms 604 KB Output is correct
4 Correct 1 ms 604 KB Output is correct
5 Correct 1 ms 604 KB Output is correct
6 Correct 1 ms 604 KB Output is correct
7 Correct 1 ms 604 KB Output is correct
8 Correct 1 ms 604 KB Output is correct
9 Correct 1 ms 348 KB Output is correct
10 Correct 1 ms 348 KB Output is correct
11 Correct 45 ms 10192 KB Output is correct
12 Correct 52 ms 13252 KB Output is correct
13 Correct 54 ms 17916 KB Output is correct
14 Correct 60 ms 24096 KB Output is correct
15 Correct 71 ms 26056 KB Output is correct
16 Correct 67 ms 28328 KB Output is correct
17 Correct 68 ms 29820 KB Output is correct
18 Correct 67 ms 28356 KB Output is correct
19 Correct 72 ms 31220 KB Output is correct
20 Correct 51 ms 16224 KB Output is correct
21 Correct 48 ms 15812 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 1 ms 604 KB Output is correct
4 Correct 1 ms 604 KB Output is correct
5 Correct 1 ms 604 KB Output is correct
6 Correct 1 ms 604 KB Output is correct
7 Correct 1 ms 604 KB Output is correct
8 Correct 1 ms 604 KB Output is correct
9 Correct 1 ms 348 KB Output is correct
10 Correct 1 ms 348 KB Output is correct
11 Correct 45 ms 10192 KB Output is correct
12 Correct 52 ms 13252 KB Output is correct
13 Correct 54 ms 17916 KB Output is correct
14 Correct 60 ms 24096 KB Output is correct
15 Correct 71 ms 26056 KB Output is correct
16 Correct 67 ms 28328 KB Output is correct
17 Correct 68 ms 29820 KB Output is correct
18 Correct 67 ms 28356 KB Output is correct
19 Correct 72 ms 31220 KB Output is correct
20 Correct 51 ms 16224 KB Output is correct
21 Correct 48 ms 15812 KB Output is correct
22 Correct 159 ms 34168 KB Output is correct
23 Correct 149 ms 33216 KB Output is correct
24 Correct 152 ms 34072 KB Output is correct
25 Correct 157 ms 37820 KB Output is correct
26 Correct 237 ms 33732 KB Output is correct
27 Correct 156 ms 32704 KB Output is correct
28 Correct 62 ms 8132 KB Output is correct
29 Correct 103 ms 19904 KB Output is correct
30 Correct 110 ms 19908 KB Output is correct
31 Correct 100 ms 21188 KB Output is correct
32 Correct 128 ms 26816 KB Output is correct