oj.uz

Submission #579940

# Submission time Handle Problem Language Result Execution time Memory
579940 2022-06-20T10:18:09 Z dxz05 One-Way Streets (CEOI17_oneway) C++17
30 / 100
 3000 ms 47196 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 (x == y) return;
    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;
}

char answer[N];
inline void solve(int TC) {
    int n, m;
    scanf("%d %d", &n, &m);

    for (int i = 1; i <= m; i++){
        int x, y;
        scanf("%d %d", &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;
    scanf("%d", &q);

    vector<pair<int, int>> important;
    while (q--){
        int x, y;
        scanf("%d %d", &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) answer[i - 1] = 'B';
        if (flag[i] == 1) answer[i - 1] = 'L';
        if (flag[i] == 2) answer[i - 1] = 'R';
    }

    printf("%s", answer);

}

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:203:13: warning: unused variable 'X' [-Wunused-variable]
  203 |         int X = x, Y = y;
      |             ^
oneway.cpp:203:20: warning: unused variable 'Y' [-Wunused-variable]
  203 |         int X = x, Y = y;
      |                    ^
oneway.cpp:131:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  131 |     scanf("%d %d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~~
oneway.cpp:135:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  135 |         scanf("%d %d", &x, &y);
      |         ~~~~~^~~~~~~~~~~~~~~~~
oneway.cpp:158:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  158 |     scanf("%d", &q);
      |     ~~~~~^~~~~~~~~~
oneway.cpp:163:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  163 |         scanf("%d %d", &x, &y);
      |         ~~~~~^~~~~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23764 KB Output is correct
2 Correct 14 ms 23836 KB Output is correct
3 Correct 15 ms 23948 KB Output is correct
4 Correct 18 ms 24020 KB Output is correct
5 Correct 26 ms 24020 KB Output is correct
6 Correct 16 ms 23892 KB Output is correct
7 Correct 24 ms 24088 KB Output is correct
8 Correct 20 ms 23972 KB Output is correct
9 Correct 15 ms 23892 KB Output is correct
10 Correct 16 ms 23892 KB Output is correct

Subtask #2
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23764 KB Output is correct
2 Correct 14 ms 23836 KB Output is correct
3 Correct 15 ms 23948 KB Output is correct
4 Correct 18 ms 24020 KB Output is correct
5 Correct 26 ms 24020 KB Output is correct
6 Correct 16 ms 23892 KB Output is correct
7 Correct 24 ms 24088 KB Output is correct
8 Correct 20 ms 23972 KB Output is correct
9 Correct 15 ms 23892 KB Output is correct
10 Correct 16 ms 23892 KB Output is correct
11 Correct 170 ms 34232 KB Output is correct
12 Correct 154 ms 35052 KB Output is correct
13 Correct 224 ms 36572 KB Output is correct
14 Correct 293 ms 39028 KB Output is correct
15 Correct 458 ms 40096 KB Output is correct
16 Correct 357 ms 45732 KB Output is correct
17 Execution timed out 3086 ms 47196 KB Time limit exceeded
18 Halted 0 ms 0 KB -

Subtask #3
0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23764 KB Output is correct
2 Correct 14 ms 23836 KB Output is correct
3 Correct 15 ms 23948 KB Output is correct
4 Correct 18 ms 24020 KB Output is correct
5 Correct 26 ms 24020 KB Output is correct
6 Correct 16 ms 23892 KB Output is correct
7 Correct 24 ms 24088 KB Output is correct
8 Correct 20 ms 23972 KB Output is correct
9 Correct 15 ms 23892 KB Output is correct
10 Correct 16 ms 23892 KB Output is correct
11 Correct 170 ms 34232 KB Output is correct
12 Correct 154 ms 35052 KB Output is correct
13 Correct 224 ms 36572 KB Output is correct
14 Correct 293 ms 39028 KB Output is correct
15 Correct 458 ms 40096 KB Output is correct
16 Correct 357 ms 45732 KB Output is correct
17 Execution timed out 3086 ms 47196 KB Time limit exceeded
18 Halted 0 ms 0 KB -