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Submission #425912

# Submission time Handle Problem Language Result Execution time Memory
425912 2021-06-13T12:19:39 Z oleh1421 One-Way Streets (CEOI17_oneway) C++17
60 / 100
 3000 ms 27012 KB 
#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
const int N=100010;
const ll mod=1000000007;
const ll inf=1e15;
int a[N],b[N];
int x[N],y[N];
vector<pair<int,int> >g[N];
int timer=0;
int tin[N],tout[N],fup[N];
bool used[N];
bool imp[N];
void dfs(int v,int pr){
    used[v]=true;
    tin[v]=fup[v]=++timer;
    for (auto cur:g[v]){
        int to=cur.first;
        int ind=cur.second;
        if (ind==pr) continue;
        if (!used[to]){
            dfs(to,ind);
            if (fup[to]>tin[v]) imp[ind]=true;
            fup[v]=min(fup[v],fup[to]);
        } else {
            fup[v]=min(fup[v],tin[to]);
        }
    }
}
int comp[N];
int num=0;
void dfs1(int v){
    comp[v]=num;
    for (auto cur:g[v]){
        int to=cur.first;
        int ind=cur.second;
        if (!imp[ind] && !comp[to]){
            dfs1(to);
        }
    }
}
vector<pair<int,int> >t[N];
const int L=20;
int up[N][L];

void dfs2(int v,int pr){
    up[v][0]=pr;
//    cout<<"0 "<<v<<" "<<pr<<endl;
    for (int i=1;i<L;i++){
        up[v][i]=up[up[v][i-1]][i-1];

    }
    used[v]=true;
    tin[v]=++timer;
    for (auto cur:t[v]){
        int to=cur.first;
        int ind=cur.second;
        if (to==pr) continue;
        dfs2(to,v);
    }

    tout[v]=timer;
}
bool upper(int a,int b){
    return (tin[a]<=tin[b] && tout[b]<=tout[a]);
}
int lca(int a,int b){
    if (upper(a,b)) return a;
    if (upper(b,a)) return b;
    for (int i=L-1;i>=0;i--){
        if (!upper(up[a][i],b)) a=up[a][i];
    }
    return up[a][0];
}
int add[N][2];
char ans[N];
void dfs3(int v,int pr,int ind){
    used[v]=true;
    for (auto cur:t[v]){
        int to=cur.first;
        int ind=cur.second;
        if (to==pr) continue;
        dfs3(to,v,ind);
        add[v][0]+=add[to][0];
        add[v][1]+=add[v][1];
    }
//    if (add[v][0] && add[v][1]) exit(1);
    if (add[v][0]){
        if (comp[a[ind]]==v) ans[ind]='R';
        else ans[ind]='L';
    } else if (add[v][1]){
        if (comp[a[ind]]==v) ans[ind]='L';
        else ans[ind]='R';
    } else {

    }

}
pair<int,int> p[N];
void dfs4(int v){
    used[v]=true;
    for (auto cur:t[v]){
        int to=cur.first;
        int ind=cur.second;
        if (used[to]) continue;
        p[to]={v,ind};
        dfs4(to);
    }

}
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n,m;cin>>n>>m;
    for (int i=1;i<=m;i++){
        cin>>a[i]>>b[i];
        g[a[i]].push_back({b[i],i});
        g[b[i]].push_back({a[i],i});
        ans[i]='B';
    }
    int k;cin>>k;
    for (int i=1;i<=k;i++){
        cin>>x[i]>>y[i];
    }
    for (int i=1;i<=n;i++){
        if (!used[i]){
            dfs(i,0);
        }
    }

    for (int i=1;i<=n;i++){
        if (!comp[i]){
            num++;
            dfs1(i);
        }
    }
    for (int v=1;v<=n;v++){
        for (auto cur:g[v]){
            int to=cur.first;
            int ind=cur.second;
            if (imp[ind]){
                t[comp[v]].push_back({comp[to],ind});
            }
        }
    }
    for (int i=1;i<=k;i++){
        x[i]=comp[x[i]];
        y[i]=comp[y[i]];
    }
    for (int i=1;i<=k;i++){
        for (int j=1;j<=n;j++) used[j]=false;

        dfs4(x[i]);
        int cur=y[i];
        while (cur!=x[i]){
            int to=p[cur].first;
            int ind=p[cur].second;
            if (comp[a[ind]]==to) {
                ans[ind]='R';
            }
            else {
                ans[ind]='L';
            }
            cur=to;
        }
    }
    for (int i=1;i<=n;i++) used[i]=false,tin[i]=0;
    tin[0]=0;
    timer=0;
    for (int i=1;i<=num;i++){
        if (!used[i]) dfs2(i,0);
    }
    tout[0]=timer;
//    for (int i=1;i<=k;i++){
//        int lc=lca(x[i],y[i]);
//        add[x[i]][0]++;
//        add[y[i]][1]++;
//        add[lc][0]--;
//        add[lc][1]--;
//    }
    for (int i=1;i<=num;i++) used[i]=false;
    for (int i=1;i<=num;i++) {
        if (!used[i]){
            dfs3(i,0,0);
        }
    }
    for (int i=1;i<=m;i++) cout<<ans[i];
    cout<<endl;
    return 0;
}

Compilation message

oneway.cpp: In function 'void dfs2(int, int)':
oneway.cpp:57:13: warning: unused variable 'ind' [-Wunused-variable]
   57 |         int ind=cur.second;
      |             ^~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 5068 KB Output is correct
2 Correct 5 ms 4968 KB Output is correct
3 Correct 4 ms 5068 KB Output is correct
4 Correct 4 ms 5196 KB Output is correct
5 Correct 5 ms 5196 KB Output is correct
6 Correct 4 ms 5068 KB Output is correct
7 Correct 6 ms 5196 KB Output is correct
8 Correct 6 ms 5180 KB Output is correct
9 Correct 4 ms 5068 KB Output is correct
10 Correct 4 ms 5032 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 5068 KB Output is correct
2 Correct 5 ms 4968 KB Output is correct
3 Correct 4 ms 5068 KB Output is correct
4 Correct 4 ms 5196 KB Output is correct
5 Correct 5 ms 5196 KB Output is correct
6 Correct 4 ms 5068 KB Output is correct
7 Correct 6 ms 5196 KB Output is correct
8 Correct 6 ms 5180 KB Output is correct
9 Correct 4 ms 5068 KB Output is correct
10 Correct 4 ms 5032 KB Output is correct
11 Correct 46 ms 10192 KB Output is correct
12 Correct 54 ms 11144 KB Output is correct
13 Correct 70 ms 12688 KB Output is correct
14 Correct 134 ms 16172 KB Output is correct
15 Correct 157 ms 17768 KB Output is correct
16 Correct 157 ms 24520 KB Output is correct
17 Correct 1294 ms 26004 KB Output is correct
18 Correct 1000 ms 24620 KB Output is correct
19 Correct 1459 ms 27012 KB Output is correct
20 Correct 55 ms 10720 KB Output is correct
21 Correct 55 ms 10660 KB Output is correct

Subtask #3
0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 5068 KB Output is correct
2 Correct 5 ms 4968 KB Output is correct
3 Correct 4 ms 5068 KB Output is correct
4 Correct 4 ms 5196 KB Output is correct
5 Correct 5 ms 5196 KB Output is correct
6 Correct 4 ms 5068 KB Output is correct
7 Correct 6 ms 5196 KB Output is correct
8 Correct 6 ms 5180 KB Output is correct
9 Correct 4 ms 5068 KB Output is correct
10 Correct 4 ms 5032 KB Output is correct
11 Correct 46 ms 10192 KB Output is correct
12 Correct 54 ms 11144 KB Output is correct
13 Correct 70 ms 12688 KB Output is correct
14 Correct 134 ms 16172 KB Output is correct
15 Correct 157 ms 17768 KB Output is correct
16 Correct 157 ms 24520 KB Output is correct
17 Correct 1294 ms 26004 KB Output is correct
18 Correct 1000 ms 24620 KB Output is correct
19 Correct 1459 ms 27012 KB Output is correct
20 Correct 55 ms 10720 KB Output is correct
21 Correct 55 ms 10660 KB Output is correct
22 Execution timed out 3066 ms 17748 KB Time limit exceeded
23 Halted 0 ms 0 KB -