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Submission #246939

# Submission time Handle Problem Language Result Execution time Memory
246939 2020-07-10T15:33:22 Z oolimry One-Way Streets (CEOI17_oneway) C++14
100 / 100
 121 ms 18572 KB 
#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> ii;

ii edges[100005];
int p[100005];
int label[100005];
int edgeId[100005];

vector<ii> adj[100005];
bool isBridge[100005];
int low[100005];
int depth[100005];
bool pathCompressed[100005];

void tarjan(int u){
	low[u] = depth[u];
	for(ii e : adj[u]){
		int v = e.first, id = e.second;
		if(depth[v] == 0){
			p[v] = u;
			depth[v] = depth[u] + 1;
			tarjan(v);
			if(low[v] > depth[u]) isBridge[id] = true;
			low[u] = min(low[u], low[v]);
			edgeId[v] = id;
		}
		else if(v != p[u]) low[u] = min(low[u], depth[v]);
	}
}

int component[100005];
int cnt = 1;
void compress(int s){
	component[s] = cnt;
	for(ii e : adj[s]){
		int v = e.first, id = e.second;
		if(component[v] == 0 && !isBridge[id]){
			compress(v);
		}
	}
}

vector<ii> tree[100005];
int ans[100005];

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	int n, m;
	cin >> n >> m;
	
	for(int i = 1;i <= m;i++){
		int a, b; cin >> a >> b;
		edges[i] = ii(a, b);
		adj[a].push_back(ii(b,i));
		adj[b].push_back(ii(a,i));
	}
	
	for(int i = 1;i <= n;i++){
		if(depth[i] != 0) continue;
		depth[i] = 1;
		tarjan(i);
	}
	
	
	for(int i = 1;i <= n;i++){
		if(component[i] != 0) continue;
		compress(i);
		cnt++;
	}
	
	/*
	for(int i = 1;i <= m;i++){
		if(isBridge[i]){
			int a = component[edges[i].first];
			int b = component[edges[i].second];
			tree[a].push_back(ii(b,i));
			tree[b].push_back(ii(a,i));
		}
	}
	*/
	
	for(int i = 1;i <= m;i++){
		if(isBridge[i]){
			int a = edges[i].first, b = edges[i].second;
			if(component[a] == component[b]) isBridge[i] = false;
		}
	}
	
	
	int Q; cin >> Q;	
	while(Q--){
		int s, t; cin >> s >> t;
		int labelS = 1, labelT = 2;
		vector<int> nodes;
		while(s != t){
			//cout << s << " " << t << endl;
			if(depth[s] >= depth[t]){
				//cout << s << " " << labelS << endl;
				if(!pathCompressed[s]) label[s] = labelS;
				pathCompressed[s] = true;
				nodes.push_back(s);
				s = p[s];
			}
			else{
				//cout << t << " " << labelT << endl;
				if(!pathCompressed[t]) label[t] = labelT;
				pathCompressed[t] = true;
				nodes.push_back(t);
				t = p[t];
			}
		}
		
		int P = s;
		for(int x : nodes){
			p[x] = P;
		}
	}
	
	for(int i = 1;i <= n;i++){
		int e = edgeId[i];
		if(e == 0) continue;
		if(!isBridge[e]) continue;
		
		int a = edges[e].first;
		int b = edges[e].second;
		
		bool swapped = false;
		
		if(depth[a] > depth[b]){
			swap(a, b);
			swapped = true;
		}
		
		//cout << a << " " << b << " " << depth[a] << " " << depth[b] << " " << label[b] << "\n";
		
		int ANS = label[b];
		if(ANS == 0) continue;
		if(swapped) ANS = 3 - ANS;
		ans[e] = ANS;
	}
	
	string S = "BLR";
	for(int i = 1;i <= m;i++){
		if(!isBridge[i]) ans[i] = 0;
		cout << S[ans[i]];
		//if(ans[i] != 0){
		//	cout << ans[i] << " " << edges[i].first << " " << edges[i].second << "\n";
		//}
	}
	
	
	return 0;
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 5120 KB Output is correct
2 Correct 7 ms 5120 KB Output is correct
3 Correct 8 ms 5248 KB Output is correct
4 Correct 8 ms 5120 KB Output is correct
5 Correct 10 ms 5120 KB Output is correct
6 Correct 7 ms 5120 KB Output is correct
7 Correct 7 ms 5120 KB Output is correct
8 Correct 7 ms 5120 KB Output is correct
9 Correct 8 ms 5120 KB Output is correct
10 Correct 9 ms 5120 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 5120 KB Output is correct
2 Correct 7 ms 5120 KB Output is correct
3 Correct 8 ms 5248 KB Output is correct
4 Correct 8 ms 5120 KB Output is correct
5 Correct 10 ms 5120 KB Output is correct
6 Correct 7 ms 5120 KB Output is correct
7 Correct 7 ms 5120 KB Output is correct
8 Correct 7 ms 5120 KB Output is correct
9 Correct 8 ms 5120 KB Output is correct
10 Correct 9 ms 5120 KB Output is correct
11 Correct 46 ms 10616 KB Output is correct
12 Correct 61 ms 11640 KB Output is correct
13 Correct 77 ms 12848 KB Output is correct
14 Correct 85 ms 13920 KB Output is correct
15 Correct 85 ms 14048 KB Output is correct
16 Correct 74 ms 12024 KB Output is correct
17 Correct 69 ms 13868 KB Output is correct
18 Correct 67 ms 12536 KB Output is correct
19 Correct 69 ms 14860 KB Output is correct
20 Correct 59 ms 11440 KB Output is correct
21 Correct 59 ms 11384 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 5120 KB Output is correct
2 Correct 7 ms 5120 KB Output is correct
3 Correct 8 ms 5248 KB Output is correct
4 Correct 8 ms 5120 KB Output is correct
5 Correct 10 ms 5120 KB Output is correct
6 Correct 7 ms 5120 KB Output is correct
7 Correct 7 ms 5120 KB Output is correct
8 Correct 7 ms 5120 KB Output is correct
9 Correct 8 ms 5120 KB Output is correct
10 Correct 9 ms 5120 KB Output is correct
11 Correct 46 ms 10616 KB Output is correct
12 Correct 61 ms 11640 KB Output is correct
13 Correct 77 ms 12848 KB Output is correct
14 Correct 85 ms 13920 KB Output is correct
15 Correct 85 ms 14048 KB Output is correct
16 Correct 74 ms 12024 KB Output is correct
17 Correct 69 ms 13868 KB Output is correct
18 Correct 67 ms 12536 KB Output is correct
19 Correct 69 ms 14860 KB Output is correct
20 Correct 59 ms 11440 KB Output is correct
21 Correct 59 ms 11384 KB Output is correct
22 Correct 104 ms 14712 KB Output is correct
23 Correct 105 ms 14840 KB Output is correct
24 Correct 119 ms 15096 KB Output is correct
25 Correct 106 ms 18572 KB Output is correct
26 Correct 99 ms 15864 KB Output is correct
27 Correct 121 ms 14840 KB Output is correct
28 Correct 49 ms 9592 KB Output is correct
29 Correct 100 ms 13432 KB Output is correct
30 Correct 97 ms 13560 KB Output is correct
31 Correct 102 ms 13816 KB Output is correct
32 Correct 89 ms 15656 KB Output is correct