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Submission #425948

# Submission time Handle Problem Language Result Execution time Memory
425948 2021-06-13T12:32:09 Z oleh1421 One-Way Streets (CEOI17_oneway) C++17
100 / 100
 255 ms 31096 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[to][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 {

    }

}
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<=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++){
        x[i]=comp[x[i]];
        y[i]=comp[y[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 4 ms 5068 KB Output is correct
3 Correct 4 ms 5068 KB Output is correct
4 Correct 4 ms 5196 KB Output is correct
5 Correct 4 ms 5196 KB Output is correct
6 Correct 4 ms 5068 KB Output is correct
7 Correct 4 ms 5196 KB Output is correct
8 Correct 4 ms 5196 KB Output is correct
9 Correct 4 ms 5068 KB Output is correct
10 Correct 4 ms 5068 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 4 ms 5068 KB Output is correct
3 Correct 4 ms 5068 KB Output is correct
4 Correct 4 ms 5196 KB Output is correct
5 Correct 4 ms 5196 KB Output is correct
6 Correct 4 ms 5068 KB Output is correct
7 Correct 4 ms 5196 KB Output is correct
8 Correct 4 ms 5196 KB Output is correct
9 Correct 4 ms 5068 KB Output is correct
10 Correct 4 ms 5068 KB Output is correct
11 Correct 53 ms 10116 KB Output is correct
12 Correct 65 ms 11156 KB Output is correct
13 Correct 65 ms 12696 KB Output is correct
14 Correct 81 ms 15976 KB Output is correct
15 Correct 87 ms 17404 KB Output is correct
16 Correct 150 ms 23720 KB Output is correct
17 Correct 165 ms 25064 KB Output is correct
18 Correct 126 ms 23876 KB Output is correct
19 Correct 140 ms 26264 KB Output is correct
20 Correct 61 ms 10692 KB Output is correct
21 Correct 55 ms 10552 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 5068 KB Output is correct
2 Correct 4 ms 5068 KB Output is correct
3 Correct 4 ms 5068 KB Output is correct
4 Correct 4 ms 5196 KB Output is correct
5 Correct 4 ms 5196 KB Output is correct
6 Correct 4 ms 5068 KB Output is correct
7 Correct 4 ms 5196 KB Output is correct
8 Correct 4 ms 5196 KB Output is correct
9 Correct 4 ms 5068 KB Output is correct
10 Correct 4 ms 5068 KB Output is correct
11 Correct 53 ms 10116 KB Output is correct
12 Correct 65 ms 11156 KB Output is correct
13 Correct 65 ms 12696 KB Output is correct
14 Correct 81 ms 15976 KB Output is correct
15 Correct 87 ms 17404 KB Output is correct
16 Correct 150 ms 23720 KB Output is correct
17 Correct 165 ms 25064 KB Output is correct
18 Correct 126 ms 23876 KB Output is correct
19 Correct 140 ms 26264 KB Output is correct
20 Correct 61 ms 10692 KB Output is correct
21 Correct 55 ms 10552 KB Output is correct
22 Correct 255 ms 25876 KB Output is correct
23 Correct 255 ms 26640 KB Output is correct
24 Correct 232 ms 26840 KB Output is correct
25 Correct 209 ms 31096 KB Output is correct
26 Correct 207 ms 27848 KB Output is correct
27 Correct 222 ms 26796 KB Output is correct
28 Correct 44 ms 10052 KB Output is correct
29 Correct 111 ms 13368 KB Output is correct
30 Correct 91 ms 13516 KB Output is correct
31 Correct 75 ms 13712 KB Output is correct
32 Correct 105 ms 19324 KB Output is correct