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Submission #462605

# Submission time Handle Problem Language Result Execution time Memory
462605 2021-08-10T23:36:58 Z JovanB One-Way Streets (CEOI17_oneway) C++17
100 / 100
 268 ms 35208 KB 
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

int cnt;

int in[100005];
int low[100005];
bool visited[100005];
vector <int> graf[100005];
vector <int> dgraf[100005];
vector <int> tree[100005];
int a[100005];
int b[100005];
int qa[100005];
int qb[100005];

void dfs1(int v, int prnt){
    low[v] = in[v] = ++cnt;
    visited[v] = 1;
    for(auto c : graf[v]){
        if(c == prnt) continue;
        if(visited[c]){
            dgraf[v].push_back(c);
            dgraf[c].push_back(v);
            low[v] = min(low[v], in[c]);
            continue;
        }
        dfs1(c, v);
        low[v] = min(low[v], low[c]);
    }
    if(!prnt) return;
    if(low[v] <= in[prnt]){
        dgraf[v].push_back(prnt);
        dgraf[prnt].push_back(v);
    }
}

int ncomp;
int comp[100005];

void dfs2(int v){
    comp[v] = ncomp;
    //cout << v << " je u " << ncomp << endl;
    for(auto c : dgraf[v]){
        if(!comp[c]) dfs2(c);
    }
}

int out[100005];
int par[100005][22];
int gore[100005];
int depth[100005];

void dfs3(int v, int prnt){
    visited[v] = 1;
    par[v][0] = prnt;
    in[v] = ++cnt;
    for(int j=1; j<18; j++){
        par[v][j] = par[par[v][j-1]][j-1];
    }
    for(auto c : tree[v]){
        //if(visited[c]) continue;
        if(c == prnt) continue;
        depth[c] = depth[v] + 1;
        dfs3(c, v);
    }
    out[v] = ++cnt;
}

bool is_parent(int x, int y){
    return in[x] <= in[y] && out[y] <= out[x];
}

int lca(int x, int y){
    if(is_parent(x, y)) return x;
    if(is_parent(y, x)) return y;
    for(int j=17; j>=0; j--){
        if(!par[x][j]) continue;
        if(!is_parent(par[x][j], y)) x = par[x][j];
    }
    return par[x][0];
}

bool cmp(pair <int, int> a, pair <int, int> b){
    return depth[a.second] < depth[b.second];
}

int main() {
    ios_base::sync_with_stdio(false);
    cout.precision(10);
    cout << fixed;
    
    int n, m, q;
    cin >> n >> m;
    for(int i=1; i<=m; i++){
        cin >> a[i] >> b[i];
        graf[a[i]].push_back(b[i]);
        graf[b[i]].push_back(a[i]);
    }
    cin >> q;
    for(int i=1; i<=q; i++){
        cin >> qa[i] >> qb[i];
    }
    for(int i=1; i<=n; i++){
        if(!visited[i]) dfs1(i, 0);
    }
    for(int i=1; i<=n; i++){
        if(!comp[i]){
            ncomp++;
            dfs2(i);
        }
    }
    for(int i=1; i<=m; i++){
        if(comp[a[i]] == comp[b[i]]) continue;
        tree[comp[a[i]]].push_back(comp[b[i]]);
        tree[comp[b[i]]].push_back(comp[a[i]]);
        //cout << comp[a[i]] << " " << comp[b[i]] << "\n";
    }
    cnt = 0;
    for(int i=1; i<=ncomp; i++) visited[i] = 0;
    for(int i=1; i<=ncomp; i++){
        if(!visited[i]){
            dfs3(i, 0);
        }
    }
    vector <pair <int, int>> queries;
    for(int i=1; i<=q; i++){
        int k = lca(comp[qa[i]], comp[qb[i]]);
        queries.push_back({comp[qa[i]], k});
    }
    sort(queries.begin(), queries.end(), cmp);
    for(auto c : queries){
        int x = c.first;
        while(x != c.second){
            if(gore[x]) break;
            gore[x] = -1;
            x = par[x][0];
        }
    }
    queries.clear();
    for(int i=1; i<=q; i++){
        int k = lca(comp[qa[i]], comp[qb[i]]);
        queries.push_back({comp[qb[i]], k});
    }
    sort(queries.begin(), queries.end(), cmp);
    for(auto c : queries){
        int x = c.first;
        while(x != c.second){
            if(gore[x]) break;
            gore[x] = 1;
            x = par[x][0];
        }
    }
    for(int i=1; i<=m; i++){
        if(comp[a[i]] == comp[b[i]]){
            cout << "B";
            continue;
        }
        if((gore[comp[a[i]]] == 1 && par[comp[a[i]]][0] == comp[b[i]]) || (gore[comp[b[i]]] == -1 && par[comp[b[i]]][0] == comp[a[i]])) cout << "L";
        else if((gore[comp[a[i]]] == -1 && par[comp[a[i]]][0] == comp[b[i]]) || (gore[comp[b[i]]] == 1 && par[comp[b[i]]][0] == comp[a[i]])) cout << "R";
        else cout << "B";
    }
    return 0;
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 7372 KB Output is correct
2 Correct 4 ms 7372 KB Output is correct
3 Correct 5 ms 7500 KB Output is correct
4 Correct 5 ms 7500 KB Output is correct
5 Correct 5 ms 7628 KB Output is correct
6 Correct 5 ms 7512 KB Output is correct
7 Correct 5 ms 7628 KB Output is correct
8 Correct 5 ms 7604 KB Output is correct
9 Correct 5 ms 7500 KB Output is correct
10 Correct 5 ms 7500 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 7372 KB Output is correct
2 Correct 4 ms 7372 KB Output is correct
3 Correct 5 ms 7500 KB Output is correct
4 Correct 5 ms 7500 KB Output is correct
5 Correct 5 ms 7628 KB Output is correct
6 Correct 5 ms 7512 KB Output is correct
7 Correct 5 ms 7628 KB Output is correct
8 Correct 5 ms 7604 KB Output is correct
9 Correct 5 ms 7500 KB Output is correct
10 Correct 5 ms 7500 KB Output is correct
11 Correct 66 ms 15032 KB Output is correct
12 Correct 68 ms 16192 KB Output is correct
13 Correct 84 ms 17772 KB Output is correct
14 Correct 96 ms 21064 KB Output is correct
15 Correct 106 ms 22468 KB Output is correct
16 Correct 131 ms 26620 KB Output is correct
17 Correct 129 ms 28696 KB Output is correct
18 Correct 115 ms 26820 KB Output is correct
19 Correct 120 ms 30016 KB Output is correct
20 Correct 71 ms 15984 KB Output is correct
21 Correct 66 ms 15660 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 7372 KB Output is correct
2 Correct 4 ms 7372 KB Output is correct
3 Correct 5 ms 7500 KB Output is correct
4 Correct 5 ms 7500 KB Output is correct
5 Correct 5 ms 7628 KB Output is correct
6 Correct 5 ms 7512 KB Output is correct
7 Correct 5 ms 7628 KB Output is correct
8 Correct 5 ms 7604 KB Output is correct
9 Correct 5 ms 7500 KB Output is correct
10 Correct 5 ms 7500 KB Output is correct
11 Correct 66 ms 15032 KB Output is correct
12 Correct 68 ms 16192 KB Output is correct
13 Correct 84 ms 17772 KB Output is correct
14 Correct 96 ms 21064 KB Output is correct
15 Correct 106 ms 22468 KB Output is correct
16 Correct 131 ms 26620 KB Output is correct
17 Correct 129 ms 28696 KB Output is correct
18 Correct 115 ms 26820 KB Output is correct
19 Correct 120 ms 30016 KB Output is correct
20 Correct 71 ms 15984 KB Output is correct
21 Correct 66 ms 15660 KB Output is correct
22 Correct 268 ms 31648 KB Output is correct
23 Correct 232 ms 29628 KB Output is correct
24 Correct 248 ms 29792 KB Output is correct
25 Correct 243 ms 35208 KB Output is correct
26 Correct 240 ms 31044 KB Output is correct
27 Correct 212 ms 29804 KB Output is correct
28 Correct 58 ms 14012 KB Output is correct
29 Correct 110 ms 18432 KB Output is correct
30 Correct 124 ms 18492 KB Output is correct
31 Correct 107 ms 19128 KB Output is correct
32 Correct 147 ms 24320 KB Output is correct