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Submission #285996

# Submission time Handle Problem Language Result Execution time Memory
285996 2020-08-29T21:33:17 Z Blagojce One-Way Streets (CEOI17_oneway) C++11
100 / 100
 438 ms 30456 KB 
#include <bits/stdc++.h>
#define fr(i, n, m) for(int i = (n); i < (m); i ++)
#define pb push_back
#define st first
#define nd second
#define pq priority_queue
#define all(x) begin(x), end(x)

using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;

const ll inf = 1e18;
const ld eps = 1e-13;
const ll mod = 1e9+7; 
const int i_inf = 1e9;
const int mxn = 1e5;
mt19937 _rand(time(NULL));
clock_t timer = clock();

int n, m;
vector<pii> g[mxn];
int ans[mxn];
int dep[mxn];
bool vis[mxn];
bool bridge[mxn];


void dfs0(int u, int ed){
	vis[u] = true;
	int mindepth = dep[u];
	for(auto e : g[u]){
		if(e.nd == ed) continue;
		if(!vis[e.st]){
			dep[e.st] = dep[u] + 1;
			dfs0(e.st, e.nd);
		}
		mindepth = min(mindepth, dep[e.st]);
	}
	if(mindepth >= dep[u]){
		bridge[ed] = true;
	}
	else{
		dep[u] = mindepth;
	}
}

int group[mxn];
void dfs1(int u, int col){
	vis[u] = true;
	group[u] = col;
	for(auto e : g[u]){
		if(vis[e.st] || bridge[e.nd]) continue;
		dfs1(e.st, col);
	}
}
vector<pii> tree[mxn];

int sparse[mxn][20];
int depth[mxn];

void dfs2(int u, int p){
	vis[u] = true;
	sparse[u][0] = p;
	fr(i, 1, 20) sparse[u][i] = sparse[sparse[u][i-1]][i-1];
	for(auto e : tree[u]){
		if(e.st == p) continue;
		depth[e.st] = depth[u] + 1;
		dfs2(e.st, u);
	}
}
int lca(int a, int b){
	int d = min(depth[a], depth[b]);
	for(int i = 19; i >= 0; i --){
		if(depth[a] - (1<<i) >= d) a = sparse[a][i];
		if(depth[b] - (1<<i) >= d) b = sparse[b][i];
	}
	if(a == b) return a;
	for(int i = 19; i >= 0; i --){
		if(sparse[a][i] != sparse[b][i]){
			a = sparse[a][i];
			b = sparse[b][i];
		}
	}
	return sparse[a][0];
}
int val1[mxn];
int val2[mxn];

void dfs3(int u, int p, int ed){
	for(auto e : tree[u]){
		if(e.st == p) continue;
		dfs3(e.st, u, e.nd);
		val1[u] += val1[e.st];
		val2[u] += val2[e.st];
	}
	if(u == p) return;
	if(val1[u] > 0){
		if(ed > 0){
			ans[ed-1] = 2;
		}else{
			ans[-ed-1] = 1;
		}
	}
	if(val2[u] > 0){
		if(ed > 0){
			ans[ed-1] = 1;
		}
		else{
			ans[-ed-1] = 2;
		}
	}
}

void solve(){
	cin >> n >> m;
	int l[m], r[m];
	fr(i, 0, m){
		int u, v;
		cin >> u >> v;
		--u, --v;
		
		l[i] = u;
		r[i] = v;
		
		if(u == v){
			continue;
		}
		g[u].pb({v, i});
		g[v].pb({u, i});
	}
	fr(i, 0, n){
		if(vis[i]) continue;
		dfs0(i, -1);
	}
	memset(vis, false, sizeof(vis));
	int col = 0;
	fr(i, 0, n){
		if(vis[i]) continue;
		dfs1(i, col);
		++col;
	}
	fr(i, 0, m){
		if(!bridge[i] || l[i] == r[i]) continue;

		int a = group[l[i]];
		int b = group[r[i]];
		
		tree[a].pb({b, i+1});
		tree[b].pb({a, -(i+1)});
	}
	memset(vis, false, sizeof(vis));
	vector<int> R;
	fr(i, 0, col){
		if(vis[i]) continue;
		dfs2(i, i);
		R.pb(i);
	}
	int p;
	cin >> p;
	bool answered[mxn];
	memset(answered, false, sizeof(answered));
	fr(i, 0, p){
		int u, v;
		cin >> u >> v;
		--u, --v;
		u = group[u];
		v = group[v];
		if(u == v) continue;
		
		int k = lca(u, v);
		
		
		val1[u] ++;
		val1[k] --;
		
		val2[v] ++;
		val2[k] --;
	}
	
	for(auto u : R){
		dfs3(u, u, 0);
	}
	
	fr(i, 0, m){
		if(ans[i] == 0) cout<<'B';
		else if(ans[i] == 1) cout<<'R';
		else cout<<'L';
	}
	cout<<endl;
	
}

int main(){
	solve();
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 5248 KB Output is correct
2 Correct 3 ms 5248 KB Output is correct
3 Correct 4 ms 5376 KB Output is correct
4 Correct 6 ms 5376 KB Output is correct
5 Correct 5 ms 5504 KB Output is correct
6 Correct 5 ms 5248 KB Output is correct
7 Correct 5 ms 5504 KB Output is correct
8 Correct 5 ms 5504 KB Output is correct
9 Correct 5 ms 5248 KB Output is correct
10 Correct 5 ms 5248 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 5248 KB Output is correct
2 Correct 3 ms 5248 KB Output is correct
3 Correct 4 ms 5376 KB Output is correct
4 Correct 6 ms 5376 KB Output is correct
5 Correct 5 ms 5504 KB Output is correct
6 Correct 5 ms 5248 KB Output is correct
7 Correct 5 ms 5504 KB Output is correct
8 Correct 5 ms 5504 KB Output is correct
9 Correct 5 ms 5248 KB Output is correct
10 Correct 5 ms 5248 KB Output is correct
11 Correct 142 ms 10104 KB Output is correct
12 Correct 147 ms 10872 KB Output is correct
13 Correct 161 ms 12152 KB Output is correct
14 Correct 184 ms 15536 KB Output is correct
15 Correct 216 ms 16884 KB Output is correct
16 Correct 234 ms 23672 KB Output is correct
17 Correct 213 ms 25208 KB Output is correct
18 Correct 223 ms 23800 KB Output is correct
19 Correct 205 ms 26360 KB Output is correct
20 Correct 142 ms 10364 KB Output is correct
21 Correct 138 ms 10744 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 5248 KB Output is correct
2 Correct 3 ms 5248 KB Output is correct
3 Correct 4 ms 5376 KB Output is correct
4 Correct 6 ms 5376 KB Output is correct
5 Correct 5 ms 5504 KB Output is correct
6 Correct 5 ms 5248 KB Output is correct
7 Correct 5 ms 5504 KB Output is correct
8 Correct 5 ms 5504 KB Output is correct
9 Correct 5 ms 5248 KB Output is correct
10 Correct 5 ms 5248 KB Output is correct
11 Correct 142 ms 10104 KB Output is correct
12 Correct 147 ms 10872 KB Output is correct
13 Correct 161 ms 12152 KB Output is correct
14 Correct 184 ms 15536 KB Output is correct
15 Correct 216 ms 16884 KB Output is correct
16 Correct 234 ms 23672 KB Output is correct
17 Correct 213 ms 25208 KB Output is correct
18 Correct 223 ms 23800 KB Output is correct
19 Correct 205 ms 26360 KB Output is correct
20 Correct 142 ms 10364 KB Output is correct
21 Correct 138 ms 10744 KB Output is correct
22 Correct 438 ms 26072 KB Output is correct
23 Correct 386 ms 26232 KB Output is correct
24 Correct 385 ms 26300 KB Output is correct
25 Correct 414 ms 30456 KB Output is correct
26 Correct 400 ms 27256 KB Output is correct
27 Correct 379 ms 26244 KB Output is correct
28 Correct 144 ms 9336 KB Output is correct
29 Correct 256 ms 12280 KB Output is correct
30 Correct 259 ms 12792 KB Output is correct
31 Correct 260 ms 12664 KB Output is correct
32 Correct 319 ms 18168 KB Output is correct