oj.uz

Submission #837957

# Submission time Handle Problem Language Result Execution time Memory
837957 2023-08-25T21:37:13 Z jamielim One-Way Streets (CEOI17_oneway) C++14
100 / 100
 226 ms 35684 KB 
#include <bits/stdc++.h>
using namespace std;
 
#define fi first
#define se second
#define mp make_pair
#define pb emplace_back
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
typedef long long ll;
typedef pair<int,int> ii;
typedef pair<ii,ii> i4;
typedef vector<int> vi;
const int MOD=1000000007;
const int INF=1012345678;
const ll LLINF=1012345678012345678LL;
const double PI=3.1415926536;
const double EPS=1e-14;
 
int n,m,p;
ii edge[100005];
vector<ii> adj[100005],adj2[100005];
bool bridge[100005];
char ans[100005];
 
int dep[100005],low[100005],ctr=1;
void dfs(int x,int pa){
	low[x]=dep[x]=ctr++;
	for(ii i:adj[x]){
		if(dep[i.fi]==0){
			dfs(i.fi,x);
			if(low[i.fi]>dep[x])bridge[abs(i.se)]=1;
			else low[x]=min(low[i.fi],low[x]);
		}else if(i.fi!=pa)low[x]=min(dep[i.fi],low[x]);
	}
}
 
int comp[100005],c=1;
void dfs2(int x){
	comp[x]=c;
	for(ii i:adj[x]){
		if(bridge[abs(i.se)])continue;
		if(comp[i.fi])continue;
		dfs2(i.fi);
	}
}
 
int par[20][100005];
int dir[20][100005];
int idx[100005];
void dfs3(int x){
	for(ii i:adj2[x]){
		if(i.fi==par[0][x]||i.fi==x)continue;
		dep[i.fi]=dep[x]+1;
		par[0][i.fi]=x;
		idx[i.fi]=-i.se;
		dfs3(i.fi);
	}
}
 
int lca(int x,int y){
	if(dep[x]>dep[y])swap(x,y);
	for(int i=19;i>=0;i--)if(dep[par[i][y]]>=dep[x])y=par[i][y];
	if(x==y)return x;
	for(int i=19;i>=0;i--)if(par[i][x]!=par[i][y])x=par[i][x],y=par[i][y];
	return par[0][x];
}
 
void direct(int x,int y,int d){
	if(x==y)return;
	for(int i=19;i>=0;i--){
		if(dep[par[i][x]]>=dep[y]){
			dir[i][x]=d;
			x=par[i][x];
		}
	}
}
 
int main(){
	scanf("%d%d",&n,&m);
	int a,b;
	for(int i=1;i<=m;i++){
		scanf("%d%d",&a,&b);
		edge[i]=mp(a,b);
		adj[a].pb(b,i);
		adj[b].pb(a,-i);
	}
	for(int i=1;i<=n;i++){
		if(!dep[i]){
			dfs(i,0);
		}
	}
	for(int i=1;i<=n;i++){
		if(!comp[i]){
			dfs2(i);
			c++;
		}
	}
	for(int i=1;i<=m;i++){
		ans[i-1]='B';
		if(bridge[i]){
			a=comp[edge[i].fi],b=comp[edge[i].se];
			adj2[a].pb(b,i);
			adj2[b].pb(a,-i);
		}
	}
	memset(dep,0,sizeof(dep));
	for(int i=1;i<c;i++){
		if(!par[0][i]){
			dep[i]=1;
			dfs3(i);
		}
	}
	for(int i=1;i<20;i++)for(int j=1;j<c;j++)par[i][j]=par[i-1][par[i-1][j]];
	
	scanf("%d",&p);
	for(int i=0;i<p;i++){
		scanf("%d%d",&a,&b);
		if(comp[a]==comp[b])continue;
		int l=lca(comp[a],comp[b]);
		direct(comp[a],l,1);
		direct(comp[b],l,-1);
	}
	
	for(int i=19;i>0;i--){
		for(int j=1;j<c;j++){
			if(dir[i][j]!=0){
				dir[i-1][j]=dir[i][j];
				dir[i-1][par[i-1][j]]=dir[i][j];
			}
		}
	}
	for(int i=1;i<c;i++){
		if(idx[i]==0)continue;
		if(dir[0][i]*idx[i]>0)ans[abs(idx[i])-1]='R';
		else if(dir[0][i]*idx[i]<0)ans[abs(idx[i])-1]='L';
	}
	printf("%s",ans);
}

Compilation message

oneway.cpp: In function 'int main()':
oneway.cpp:80:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   80 |  scanf("%d%d",&n,&m);
      |  ~~~~~^~~~~~~~~~~~~~
oneway.cpp:83:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   83 |   scanf("%d%d",&a,&b);
      |   ~~~~~^~~~~~~~~~~~~~
oneway.cpp:116:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  116 |  scanf("%d",&p);
      |  ~~~~~^~~~~~~~~
oneway.cpp:118:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  118 |   scanf("%d%d",&a,&b);
      |   ~~~~~^~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5460 KB Output is correct
2 Correct 3 ms 5508 KB Output is correct
3 Correct 3 ms 5588 KB Output is correct
4 Correct 3 ms 5716 KB Output is correct
5 Correct 3 ms 5716 KB Output is correct
6 Correct 2 ms 5588 KB Output is correct
7 Correct 3 ms 5788 KB Output is correct
8 Correct 3 ms 5716 KB Output is correct
9 Correct 3 ms 5588 KB Output is correct
10 Correct 3 ms 5588 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5460 KB Output is correct
2 Correct 3 ms 5508 KB Output is correct
3 Correct 3 ms 5588 KB Output is correct
4 Correct 3 ms 5716 KB Output is correct
5 Correct 3 ms 5716 KB Output is correct
6 Correct 2 ms 5588 KB Output is correct
7 Correct 3 ms 5788 KB Output is correct
8 Correct 3 ms 5716 KB Output is correct
9 Correct 3 ms 5588 KB Output is correct
10 Correct 3 ms 5588 KB Output is correct
11 Correct 29 ms 11596 KB Output is correct
12 Correct 32 ms 12568 KB Output is correct
13 Correct 37 ms 14032 KB Output is correct
14 Correct 43 ms 17136 KB Output is correct
15 Correct 50 ms 18380 KB Output is correct
16 Correct 57 ms 24524 KB Output is correct
17 Correct 61 ms 30832 KB Output is correct
18 Correct 59 ms 25676 KB Output is correct
19 Correct 60 ms 32076 KB Output is correct
20 Correct 32 ms 11992 KB Output is correct
21 Correct 31 ms 11980 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5460 KB Output is correct
2 Correct 3 ms 5508 KB Output is correct
3 Correct 3 ms 5588 KB Output is correct
4 Correct 3 ms 5716 KB Output is correct
5 Correct 3 ms 5716 KB Output is correct
6 Correct 2 ms 5588 KB Output is correct
7 Correct 3 ms 5788 KB Output is correct
8 Correct 3 ms 5716 KB Output is correct
9 Correct 3 ms 5588 KB Output is correct
10 Correct 3 ms 5588 KB Output is correct
11 Correct 29 ms 11596 KB Output is correct
12 Correct 32 ms 12568 KB Output is correct
13 Correct 37 ms 14032 KB Output is correct
14 Correct 43 ms 17136 KB Output is correct
15 Correct 50 ms 18380 KB Output is correct
16 Correct 57 ms 24524 KB Output is correct
17 Correct 61 ms 30832 KB Output is correct
18 Correct 59 ms 25676 KB Output is correct
19 Correct 60 ms 32076 KB Output is correct
20 Correct 32 ms 11992 KB Output is correct
21 Correct 31 ms 11980 KB Output is correct
22 Correct 226 ms 32352 KB Output is correct
23 Correct 198 ms 29284 KB Output is correct
24 Correct 158 ms 27148 KB Output is correct
25 Correct 208 ms 35684 KB Output is correct
26 Correct 204 ms 31844 KB Output is correct
27 Correct 199 ms 29760 KB Output is correct
28 Correct 26 ms 9676 KB Output is correct
29 Correct 58 ms 12744 KB Output is correct
30 Correct 60 ms 12968 KB Output is correct
31 Correct 50 ms 13156 KB Output is correct
32 Correct 123 ms 20532 KB Output is correct