oj.uz

Submission #971459

# Submission time Handle Problem Language Result Execution time Memory
971459 2024-04-28T14:38:27 Z efedmrlr One-Way Streets (CEOI17_oneway) C++17
100 / 100
 134 ms 32036 KB 
#include <bits/stdc++.h>

#define lli long long int
#define ld long double
#define pb push_back
#define MP make_pair
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define REP(i, n) for(int i = 0; (i) < (n); (i)++)

using namespace std;

void fastio() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
}

const int N = 1e5 + 5;
const int INF = 1e9 + 500;
const int LGN = 20;


int n, m;
vector<array<int, 2> > edg(N);
vector<char> res(N, '$');
struct Bridge {
    vector<vector<array<int, 2> > > adj;
    vector<int> tin, low;
    vector<bool> vis;
    vector<bool> isBr;
    int tim = 0;
    int curc = 0;
    Bridge() {
    }
    void reset() {
        tin.assign(N, -1);
        low.assign(N, -1);
        vis.assign(N, 0);
        isBr.assign(N, 0);
        adj.assign(N, vector<array<int, 2> >());
        tim = 0;
    }
    void dfs(int node, int pedg) {
        tin[node] = low[node] = tim++;
        vis[node] = 1;
        for(auto c : adj[node]) {
            if(c[1] == pedg) continue;
            if(vis[c[0]]) {
                low[node] = min(low[node], tin[c[0]]);
            }
            else {
                dfs(c[0], c[1]);
                low[node] = min(low[node], low[c[0]]);
                if(low[c[0]] > tin[node]) {
                    //bridge found
                    isBr[c[1]] = 1;
                }
            }
        }
    }
    
    void dfs2(int node, int par, vector<int> &comp) {
        for(auto c : adj[node]) {
            if(comp[c[0]] != -1 || isBr[c[1]]) {
                continue;
            }
            comp[c[0]] = comp[node];
            dfs2(c[0], node, comp);
        }
    }
    void find_comp(vector<int> &comp) {
        curc = 0;
        comp.assign(n + 1, -1);
        for(int i = 1; i <= n; i++) {
            if(comp[i] != -1) continue;
            comp[i] = curc++;
            dfs2(i, i, comp);
        }
    }

};


struct Tre {
    vector<vector<array<int, 2> > > adj;
    vector<int> head;
    vector<int> subt, dep;
    vector<int> p, pedg;
    vector<int> dir;
    int n;
    Tre() {
        adj.assign(N, vector<array<int, 2> >());
        subt.assign(N, -1);
        dep.assign(N, 0);
        p.assign(N, 0);
        head.assign(N, 0);
        pedg.assign(N, m);
        dir.assign(N, 0);
        
    }
    void dfssz(int node) {
        subt[node] = 1;
        for(auto &c : adj[node]) {
            p[c[0]] = node; pedg[c[0]] = c[1];
            adj[c[0]].erase(find(all(adj[c[0]]), array<int,2>({node, c[1]})));
            dfssz(c[0]);
            subt[node] += subt[c[0]];
            if(subt[adj[node][0][0]] < subt[c[0]]) {
                swap(adj[node][0], c);
            }
        }
    }
    void dfshld(int node) {
        for(auto c : adj[node]) {
            head[c[0]] = (c == adj[node][0]) ? head[node] : c[0];
            dep[c[0]] = dep[node] + 1;
            dfshld(c[0]); 
        }
    }   
    int lca(int x, int y) {
        while(head[x] != head[y]) {
            if(dep[head[x]] < dep[head[y]]) swap(x, y);
            x = p[head[x]];
        }
        if(dep[x] < dep[y]) {
            swap(x, y);
        }
        return y;
    }
    void init(int curc) {
        n = curc;
        for(int i = 0; i < n; i++) {
            p[i] = i;
        }
        for(int i = 0; i < n; i++) {
            if(subt[i] != -1) continue;
            dep[i] = 0; dfssz(i);
            head[i] = i; dfshld(i);
        }
    }
    void mark(int x, bool b) {
        if(b) {
            dir[x] = 2;
        }
        else {
            dir[x] = 1;
        }
    }

};


void solve() {
    cin >> n >> m;
    for(int i = 0; i < m; i++) {
        cin >> edg[i][0] >> edg[i][1];
    }
    Bridge br;
    br.reset();
    for(int i = 0; i < m; i++) {
        br.adj[edg[i][0]].pb({edg[i][1], i});
        br.adj[edg[i][1]].pb({edg[i][0], i});
    }
    for(int i = 1; i<=n; i++) {
        if(br.vis[i]) continue;
        br.dfs(i, m);  
    }
    vector<int> cmp;
    br.find_comp(cmp);
    // for(int i = 0; i < m; i++) {
    //     if(br.isBr[i]) {
    //         cout << "i:" << i << " a:" << edg[i][0] << " b:" << edg[i][1] << "\n";
    //     }
    // }
    // for(int i = 1; i <= n; i++) {
    //     cout << "i: " << i << " " << cmp[i] << " ";
    // }
    // cout << endl;
    Tre t;
    
    for(int i = 0; i < m; i++) {
        if(!br.isBr[i]) {
            // cout << "not bridge:" << i << "\n";
            res[i] = 'B';
        }
        else {
            
            edg[i] = {cmp[edg[i][0]], cmp[edg[i][1]]};
            t.adj[edg[i][0]].pb({edg[i][1], i});
            t.adj[edg[i][1]].pb({edg[i][0], i});
            // cout << edg[i][0] << " edg" << edg[i][1] << "\n";
        }
    }
    // cout << br.curc << " curc\n" << endl;
    t.init(br.curc);
    // for(int i = 0; i < br.curc; i++) {
    //     cout << "i:" << i <<" p:" << t.p[i] << "pedg:" << t.pedg [i] << endl;
    // }
    int p;
    cin >> p;
    vector<array<int, 3> > tmp;
    REP(i, p) {
        int x, y;
        cin >> x >> y;
        x = cmp[x]; y = cmp[y];
        if(x == y) continue;
        int lc = t.lca(x, y);
        tmp.pb({t.dep[lc], x, 0});
        tmp.pb({t.dep[lc], y, 1});
    }
    sort(all(tmp));
    for(auto c : tmp) {
        int x = c[1];
        while(t.dep[x] > c[0] && t.dir[x] == 0) {
            t.mark(x, c[2]);
            x = t.p[x];
        }
    }
    for(int i = 0; i < t.n; i++) {
        if(t.p[i] == i) continue;
        int cur = t.pedg[i];
        if(t.dir[i] == 0) {
            res[cur] = 'B';
            continue;
        }
        if(edg[cur][0] == i) {
            if(t.dir[i] == 1) {
                res[cur] = 'R';
            } 
            else {
                res[cur] = 'L';
            }
        }
        else {
            if(t.dir[i] == 1) {
                res[cur] = 'L';
            } 
            else {
                res[cur] = 'R';
            }
        }
    }
    for(int i = 0; i < m; i++) {
        cout << res[i];
    }
    cout << "\n";
}

signed main() {
    fastio();
    solve();
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9052 KB Output is correct
2 Correct 5 ms 9032 KB Output is correct
3 Correct 4 ms 9052 KB Output is correct
4 Correct 5 ms 9304 KB Output is correct
5 Correct 4 ms 9308 KB Output is correct
6 Correct 4 ms 9052 KB Output is correct
7 Correct 5 ms 9308 KB Output is correct
8 Correct 5 ms 9308 KB Output is correct
9 Correct 5 ms 9052 KB Output is correct
10 Correct 4 ms 9052 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9052 KB Output is correct
2 Correct 5 ms 9032 KB Output is correct
3 Correct 4 ms 9052 KB Output is correct
4 Correct 5 ms 9304 KB Output is correct
5 Correct 4 ms 9308 KB Output is correct
6 Correct 4 ms 9052 KB Output is correct
7 Correct 5 ms 9308 KB Output is correct
8 Correct 5 ms 9308 KB Output is correct
9 Correct 5 ms 9052 KB Output is correct
10 Correct 4 ms 9052 KB Output is correct
11 Correct 32 ms 14364 KB Output is correct
12 Correct 38 ms 15020 KB Output is correct
13 Correct 37 ms 15928 KB Output is correct
14 Correct 44 ms 17080 KB Output is correct
15 Correct 51 ms 17360 KB Output is correct
16 Correct 66 ms 18236 KB Output is correct
17 Correct 68 ms 21328 KB Output is correct
18 Correct 63 ms 18332 KB Output is correct
19 Correct 65 ms 23436 KB Output is correct
20 Correct 37 ms 14672 KB Output is correct
21 Correct 32 ms 14424 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9052 KB Output is correct
2 Correct 5 ms 9032 KB Output is correct
3 Correct 4 ms 9052 KB Output is correct
4 Correct 5 ms 9304 KB Output is correct
5 Correct 4 ms 9308 KB Output is correct
6 Correct 4 ms 9052 KB Output is correct
7 Correct 5 ms 9308 KB Output is correct
8 Correct 5 ms 9308 KB Output is correct
9 Correct 5 ms 9052 KB Output is correct
10 Correct 4 ms 9052 KB Output is correct
11 Correct 32 ms 14364 KB Output is correct
12 Correct 38 ms 15020 KB Output is correct
13 Correct 37 ms 15928 KB Output is correct
14 Correct 44 ms 17080 KB Output is correct
15 Correct 51 ms 17360 KB Output is correct
16 Correct 66 ms 18236 KB Output is correct
17 Correct 68 ms 21328 KB Output is correct
18 Correct 63 ms 18332 KB Output is correct
19 Correct 65 ms 23436 KB Output is correct
20 Correct 37 ms 14672 KB Output is correct
21 Correct 32 ms 14424 KB Output is correct
22 Correct 134 ms 25316 KB Output is correct
23 Correct 121 ms 22216 KB Output is correct
24 Correct 119 ms 22216 KB Output is correct
25 Correct 108 ms 32036 KB Output is correct
26 Correct 116 ms 24688 KB Output is correct
27 Correct 131 ms 22448 KB Output is correct
28 Correct 26 ms 12496 KB Output is correct
29 Correct 62 ms 19320 KB Output is correct
30 Correct 71 ms 18196 KB Output is correct
31 Correct 54 ms 17356 KB Output is correct
32 Correct 90 ms 22404 KB Output is correct