oj.uz

Submission #579937

# Submission time Handle Problem Language Result Execution time Memory
579937 2022-06-20T10:10:48 Z dxz05 One-Way Streets (CEOI17_oneway) C++14
30 / 100
 3000 ms 47208 KB 
#pragma GCC optimize("Ofast,O2,O3,unroll-loops")
#pragma GCC target("avx2")

#include <bits/stdc++.h>

#include <random>

using namespace std;

void debug_out() { cerr << endl; }

template<typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << "[" << H << "]";
    debug_out(T...);
}

#ifdef dddxxz
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

#define SZ(s) ((int)s.size())
#define all(x) (x).begin(), (x).end()
#define lla(x) (x).rbegin(), (x).rend()
#define bpc(x) __builtin_popcount(x)
#define bpcll(x) __builtin_popcountll(x)

clock_t startTime;

double getCurrentTime() {
    return (double) (clock() - startTime) / CLOCKS_PER_SEC;
}

#define MP make_pair

typedef long long ll;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
const double eps = 0.000001;
const int MOD = 1e9 + 7;
const int INF = 1000000101;
const long long LLINF = 1223372000000000555;
const int N = 1e6 + 3e2;
const int M = 1111;

int eu[N], ev[N];

vector<int> g[N];

int flag[N];

bool used[N];

set<pair<int, int>> bridges;

set<pair<int, int>> trash;

inline void bridge(int x, int y){
    if (trash.count(MP(x, y))) return;
    if (trash.count(MP(y, x))) return;
    bridges.insert(MP(x, y));
}

int tin[N], fup[N], timer = 0;
inline void dfs(int v, int p){
    tin[v] = fup[v] = ++timer;

    used[v] = true;
    for (int u : g[v]){
        if (u == p) continue;

        if (!used[u]){
            dfs(u, v);
            fup[v] = min(fup[v], fup[u]);
            if (fup[u] > tin[v]) bridge(u, v);
        } else {
            fup[v] = min(fup[v], tin[u]);
        }

    }
}

int p[N];

inline int find(int x){
    return (x == p[x] ? x : p[x] = find(p[x]));
}

inline void unite(int x, int y){
    x = find(x);
    y = find(y);
    if (rng() & 1) swap(x, y);
    p[x] = y;
}

inline void bfs(int x, vector<int> &d){
    queue<int> q;
    fill(all(d), INF);
    d[x] = 0;
    q.push(x);

    while (!q.empty()){
        x = q.front();
        q.pop();
        for (int y : g[x]){
            if (d[y] == INF){
                d[y] = d[x] + 1;
                q.push(y);
            }
        }
    }
}

map<pair<int, int>, int> mp;

void SetLeft(int x, int y){
    int i = mp.count(MP(x, y)) ? mp[MP(x, y)] : mp[MP(y, x)];
    flag[i] = 1;
}

void SetRight(int x, int y){
    int i = mp.count(MP(x, y)) ? mp[MP(x, y)] : mp[MP(y, x)];
    flag[i] = 2;
}

void solve(int TC) {
    int n, m;
    cin >> n >> m;

    for (int i = 1; i <= m; i++){
        int x, y;
        cin >> x >> y;

        eu[i] = x, ev[i] = y;

        if (mp.count(MP(x, y)) || mp.count(MP(y, x))){
            int ii = (mp.count(MP(x, y)) ? mp[MP(x, y)] : mp[MP(y, x)]);
            flag[i] = flag[ii] = 3;
            trash.insert(MP(x, y));
            continue;
        }

        if (x == y){
            flag[i] = 3;
            continue;
        }

        mp[MP(x, y)] = i;

        g[x].push_back(y);
        g[y].push_back(x);
    }

    int q;
    cin >> q;

    vector<pair<int, int>> important;
    while (q--){
        int x, y;
        cin >> x >> y;
        important.emplace_back(x, y);
    }

    for (int i = 1; i <= n; i++){
        if (!used[i]) dfs(i, i);
    }

    for (int i = 1; i <= m; i++){
        int x = eu[i], y = ev[i];
        if (!bridges.count(MP(x, y)) && !bridges.count(MP(y, x))) flag[i] = 3;
    }

    auto _br = bridges;
    bridges.clear();
    for (auto now : _br){
        if (mp.find(now) == mp.end()) swap(now.first, now.second);
        bridges.insert(now);
    }

    iota(p + 1, p + n + 1, 1);

    for (int i = 1; i <= m; i++){
        if (flag[i] == 3) unite(eu[i], ev[i]);
    }

    for (int i = 1; i <= n; i++) g[i].clear();

    int root = n;

    for (int i = 1; i <= m; i++){
        int x = find(eu[i]), y = find(ev[i]);
        root = min({root, x, y});
        if (x != y){
            g[x].push_back(y);
            g[y].push_back(x);
        }
    }

    for (auto [x, y] : important){
        int X = x, Y = y;
        x = find(x), y = find(y);

        if (x == y) continue;

        vector<int> dx(n + 1), dy(n + 1);
        bfs(x, dx);
        bfs(y, dy);

        for (auto [u, v] : bridges){
            int U = u, V = v;

            u = find(u), v = find(v);

            int dist = min(dx[u] + dy[v], dx[v] + dy[u]) + 1;
            if (dist != dx[y]) continue;

            if (dx[u] + dy[v] + 1 == dist){
                SetRight(U, V);
            } else {
                SetLeft(U, V);
            }

        }

    }

    for (int i = 1; i <= m; i++){
        if (flag[i] == 0 || flag[i] == 3) cout << 'B';
        if (flag[i] == 1) cout << 'L';
        if (flag[i] == 2) cout << 'R';
    }

}

int main() {
    startTime = clock();
    ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

#ifdef dddxxz
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif

    int TC = 1;
    //    cin >> TC;

    for (int test = 1; test <= TC; test++) {
        //debug(test);
        //cout << "Case #" << test << ": ";
        solve(test);
    }

#ifdef dddxxz
    cerr << endl << "Time: " << int(getCurrentTime() * 1000) << " ms" << endl;
#endif

    return 0;
}

Compilation message

oneway.cpp: In function 'void solve(int)':
oneway.cpp:200:15: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
  200 |     for (auto [x, y] : important){
      |               ^
oneway.cpp:210:19: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
  210 |         for (auto [u, v] : bridges){
      |                   ^
oneway.cpp:201:13: warning: unused variable 'X' [-Wunused-variable]
  201 |         int X = x, Y = y;
      |             ^
oneway.cpp:201:20: warning: unused variable 'Y' [-Wunused-variable]
  201 |         int X = x, Y = y;
      |                    ^

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 15 ms 23764 KB Output is correct
2 Correct 13 ms 23808 KB Output is correct
3 Correct 16 ms 23892 KB Output is correct
4 Correct 17 ms 24056 KB Output is correct
5 Correct 26 ms 24016 KB Output is correct
6 Correct 17 ms 23876 KB Output is correct
7 Correct 23 ms 24020 KB Output is correct
8 Correct 20 ms 24100 KB Output is correct
9 Correct 16 ms 23892 KB Output is correct
10 Correct 15 ms 23872 KB Output is correct

Subtask #2
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 15 ms 23764 KB Output is correct
2 Correct 13 ms 23808 KB Output is correct
3 Correct 16 ms 23892 KB Output is correct
4 Correct 17 ms 24056 KB Output is correct
5 Correct 26 ms 24016 KB Output is correct
6 Correct 17 ms 23876 KB Output is correct
7 Correct 23 ms 24020 KB Output is correct
8 Correct 20 ms 24100 KB Output is correct
9 Correct 16 ms 23892 KB Output is correct
10 Correct 15 ms 23872 KB Output is correct
11 Correct 137 ms 34220 KB Output is correct
12 Correct 170 ms 35032 KB Output is correct
13 Correct 199 ms 36464 KB Output is correct
14 Correct 353 ms 39072 KB Output is correct
15 Correct 380 ms 40132 KB Output is correct
16 Correct 352 ms 45656 KB Output is correct
17 Execution timed out 3082 ms 47208 KB Time limit exceeded
18 Halted 0 ms 0 KB -

Subtask #3
0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 15 ms 23764 KB Output is correct
2 Correct 13 ms 23808 KB Output is correct
3 Correct 16 ms 23892 KB Output is correct
4 Correct 17 ms 24056 KB Output is correct
5 Correct 26 ms 24016 KB Output is correct
6 Correct 17 ms 23876 KB Output is correct
7 Correct 23 ms 24020 KB Output is correct
8 Correct 20 ms 24100 KB Output is correct
9 Correct 16 ms 23892 KB Output is correct
10 Correct 15 ms 23872 KB Output is correct
11 Correct 137 ms 34220 KB Output is correct
12 Correct 170 ms 35032 KB Output is correct
13 Correct 199 ms 36464 KB Output is correct
14 Correct 353 ms 39072 KB Output is correct
15 Correct 380 ms 40132 KB Output is correct
16 Correct 352 ms 45656 KB Output is correct
17 Execution timed out 3082 ms 47208 KB Time limit exceeded
18 Halted 0 ms 0 KB -