oj.uz

Submission #223076

# Submission time Handle Problem Language Result Execution time Memory
223076 2020-04-14T16:12:33 Z jamielim One-Way Streets (CEOI17_oneway) C++14
100 / 100
 363 ms 31084 KB 
#include <bits/stdc++.h>
using namespace std;
const int MAXN=100005;
int n,m;
pair<int,int> edge[MAXN];
vector<pair<int,int> > adj[MAXN];

int par[MAXN];
int dep[MAXN];
int low[MAXN];
bool vis[MAXN];
bool bri[MAXN];
int ctr=0;
void dfs(int x){
	vis[x]=1;
	dep[x]=low[x]=ctr++;
	for(int i=0;i<(int)adj[x].size();i++){
		int y=adj[x][i].first;
		if(!vis[y]){ //not yet visited
			par[y]=x;
			dfs(y);
			if(low[y]>dep[x])bri[adj[x][i].second]=1;
			low[x]=min(low[x],low[y]);
		}else if(y!=par[x])low[x]=min(low[x],dep[y]); //visited and is not parent
	}
}
 
int cc[MAXN];
int c=0;
void comp(int x){
	cc[x]=c;
	for(int i=0;i<(int)adj[x].size();i++){
		if(!bri[adj[x][i].second]&&cc[adj[x][i].first]==-1)comp(adj[x][i].first);
	}
}

vector<pair<int,int> > adj2[MAXN];

pair<int,int> q[MAXN];
vector<pair<int,int> > r;
int pa[MAXN][19],idx[MAXN];
int ldep[MAXN];
void dfs2(int x){
	vis[x]=1;
	for(int i=0;i<(int)(adj2[x].size());i++){
		int y=adj2[x][i].first;
		if(!vis[y]){
			pa[y][0]=x;idx[y]=adj2[x][i].second;
			ldep[y]=ldep[x]+1;
			dfs2(y);
		}
	}
}
int lca(int x,int y){
    if(x==y)return x;
    if(ldep[x]<ldep[y])swap(x,y);
    for(int i=18;i>=0;i--){
        if(pa[x][i]!=-1&&ldep[pa[x][i]]>=ldep[y])x=pa[x][i];
    }
    if(x==y)return x;
    for(int i=18;i>=0;i--){
        if(pa[x][i]!=pa[y][i]){x=pa[x][i];y=pa[y][i];}
    }
    return pa[x][0];
}
 
int ans[MAXN]; //0 B, 1 R, -1 L
void dir(int x,int y,int d){
	if(x==y)return;
	if(ans[idx[x]]!=0)return;
	int a=edge[idx[x]].first,b=edge[idx[x]].second;
	if(x==cc[a]){
		ans[idx[x]]=d;dir(cc[b],y,d);
	}else{
		ans[idx[x]]=-d;dir(cc[a],y,d);
	}
}
 
int main(){
	scanf("%d%d",&n,&m);
	memset(par,-1,sizeof(par));memset(dep,-1,sizeof(dep));memset(low,-1,sizeof(low));
	memset(cc,-1,sizeof(cc));
	memset(pa,-1,sizeof(pa));memset(idx,-1,sizeof(idx));memset(ldep,-1,sizeof(ldep));
	int a,b;
	for(int i=0;i<m;i++){
		scanf("%d%d",&a,&b);a--;b--;edge[i]=make_pair(a,b);
		adj[a].push_back(make_pair(b,i));adj[b].push_back(make_pair(a,i));
	}
	for(int i=0;i<n;i++)if(!vis[i])dfs(i);
	//for(int i=0;i<m;i++)if(bri[i])printf("1 ");else printf("0 ");printf("\n");
	for(int i=0;i<n;i++)if(cc[i]==-1){comp(i);c++;}
	for(int i=0;i<m;i++){
		if(bri[i]){
			a=edge[i].first,b=edge[i].second;
			adj2[cc[a]].push_back(make_pair(cc[b],i));adj2[cc[b]].push_back(make_pair(cc[a],i));
		}
	}
	//for(int i=0;i<n;i++)printf("%d ",cc[i]);printf("\n");
	for(int i=0;i<c;i++)vis[i]=0; for(int i=0;i<c;i++)if(!vis[i]){ldep[i]=0;dfs2(i);}
	for(int i=1;i<18;i++)for(int j=0;j<c;j++)if(pa[j][i-1]!=-1)pa[j][i]=pa[pa[j][i-1]][i-1];
	int p;scanf("%d",&p);
	for(int i=0;i<p;i++){
		scanf("%d%d",&q[i].first,&q[i].second);q[i].first--;q[i].second--;
		if(cc[q[i].first]==cc[q[i].second])continue;
		r.push_back(make_pair(ldep[lca(cc[q[i].first],cc[q[i].second])],i)); // bugged at least 5 submissions forgetting to sort by depth
	}
	sort(r.begin(),r.end());
	for(int i=0;i<(int)r.size();i++){
		a=q[r[i].second].first,b=q[r[i].second].second;
		//printf("%d->%d->%d\n",a,r[i].first,b);
		int l=lca(cc[a],cc[b]);
		dir(cc[a],l,1);
		dir(cc[b],l,-1);
	}
	for(int i=0;i<m;i++){
		if(ans[i]==0)printf("B");
		else if(ans[i]==1)printf("R");
		else printf("L");
	}
}

Compilation message

oneway.cpp: In function 'int main()':
oneway.cpp:99:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for(int i=0;i<c;i++)vis[i]=0; for(int i=0;i<c;i++)if(!vis[i]){ldep[i]=0;dfs2(i);}
  ^~~
oneway.cpp:99:32: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
  for(int i=0;i<c;i++)vis[i]=0; for(int i=0;i<c;i++)if(!vis[i]){ldep[i]=0;dfs2(i);}
                                ^~~
oneway.cpp:80:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m);
  ~~~~~^~~~~~~~~~~~~~
oneway.cpp:86:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&a,&b);a--;b--;edge[i]=make_pair(a,b);
   ~~~~~^~~~~~~~~~~~~~
oneway.cpp:101:13: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  int p;scanf("%d",&p);
        ~~~~~^~~~~~~~~
oneway.cpp:103:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&q[i].first,&q[i].second);q[i].first--;q[i].second--;
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 14848 KB Output is correct
2 Correct 13 ms 14848 KB Output is correct
3 Correct 13 ms 14848 KB Output is correct
4 Correct 13 ms 14976 KB Output is correct
5 Correct 14 ms 14976 KB Output is correct
6 Correct 13 ms 14848 KB Output is correct
7 Correct 14 ms 14976 KB Output is correct
8 Correct 14 ms 14848 KB Output is correct
9 Correct 13 ms 14848 KB Output is correct
10 Correct 13 ms 14848 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 14848 KB Output is correct
2 Correct 13 ms 14848 KB Output is correct
3 Correct 13 ms 14848 KB Output is correct
4 Correct 13 ms 14976 KB Output is correct
5 Correct 14 ms 14976 KB Output is correct
6 Correct 13 ms 14848 KB Output is correct
7 Correct 14 ms 14976 KB Output is correct
8 Correct 14 ms 14848 KB Output is correct
9 Correct 13 ms 14848 KB Output is correct
10 Correct 13 ms 14848 KB Output is correct
11 Correct 63 ms 20472 KB Output is correct
12 Correct 85 ms 21368 KB Output is correct
13 Correct 83 ms 22136 KB Output is correct
14 Correct 95 ms 23048 KB Output is correct
15 Correct 99 ms 23412 KB Output is correct
16 Correct 130 ms 24568 KB Output is correct
17 Correct 123 ms 25848 KB Output is correct
18 Correct 122 ms 24956 KB Output is correct
19 Correct 119 ms 26872 KB Output is correct
20 Correct 77 ms 20752 KB Output is correct
21 Correct 70 ms 20984 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 14848 KB Output is correct
2 Correct 13 ms 14848 KB Output is correct
3 Correct 13 ms 14848 KB Output is correct
4 Correct 13 ms 14976 KB Output is correct
5 Correct 14 ms 14976 KB Output is correct
6 Correct 13 ms 14848 KB Output is correct
7 Correct 14 ms 14976 KB Output is correct
8 Correct 14 ms 14848 KB Output is correct
9 Correct 13 ms 14848 KB Output is correct
10 Correct 13 ms 14848 KB Output is correct
11 Correct 63 ms 20472 KB Output is correct
12 Correct 85 ms 21368 KB Output is correct
13 Correct 83 ms 22136 KB Output is correct
14 Correct 95 ms 23048 KB Output is correct
15 Correct 99 ms 23412 KB Output is correct
16 Correct 130 ms 24568 KB Output is correct
17 Correct 123 ms 25848 KB Output is correct
18 Correct 122 ms 24956 KB Output is correct
19 Correct 119 ms 26872 KB Output is correct
20 Correct 77 ms 20752 KB Output is correct
21 Correct 70 ms 20984 KB Output is correct
22 Correct 363 ms 28784 KB Output is correct
23 Correct 279 ms 27504 KB Output is correct
24 Correct 244 ms 27760 KB Output is correct
25 Correct 304 ms 31084 KB Output is correct
26 Correct 307 ms 28648 KB Output is correct
27 Correct 273 ms 27632 KB Output is correct
28 Correct 64 ms 19576 KB Output is correct
29 Correct 122 ms 23280 KB Output is correct
30 Correct 127 ms 23660 KB Output is correct
31 Correct 108 ms 23032 KB Output is correct
32 Correct 191 ms 26604 KB Output is correct