oj.uz

Submission #579942

# Submission time Handle Problem Language Result Execution time Memory
579942 2022-06-20T10:21:14 Z dxz05 One-Way Streets (CEOI17_oneway) C++17
30 / 100
 3000 ms 47812 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;
}

int q[N];
inline void bfs(int x, vector<int> &d){
    fill(all(d), INF);
    d[x] = 0;
    int sz = 1;
    q[0] = x;

    for (int i = 0; i < sz; i++){
        x = q[i];
        for (int y : g[x]){
            if (d[y] == INF){
                d[y] = d[x] + 1;
                q[sz++] = 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 qu;
    scanf("%d", &qu);

    vector<pair<int, int>> important;
    while (qu--){
        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", &qu);
      |     ~~~~~^~~~~~~~~~~
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 23868 KB Output is correct
3 Correct 14 ms 23892 KB Output is correct
4 Correct 18 ms 24020 KB Output is correct
5 Correct 24 ms 24020 KB Output is correct
6 Correct 20 ms 23892 KB Output is correct
7 Correct 24 ms 24020 KB Output is correct
8 Correct 21 ms 24020 KB Output is correct
9 Correct 15 ms 23896 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 23868 KB Output is correct
3 Correct 14 ms 23892 KB Output is correct
4 Correct 18 ms 24020 KB Output is correct
5 Correct 24 ms 24020 KB Output is correct
6 Correct 20 ms 23892 KB Output is correct
7 Correct 24 ms 24020 KB Output is correct
8 Correct 21 ms 24020 KB Output is correct
9 Correct 15 ms 23896 KB Output is correct
10 Correct 16 ms 23892 KB Output is correct
11 Correct 137 ms 34248 KB Output is correct
12 Correct 159 ms 35008 KB Output is correct
13 Correct 184 ms 36416 KB Output is correct
14 Correct 268 ms 39100 KB Output is correct
15 Correct 367 ms 40052 KB Output is correct
16 Correct 404 ms 45992 KB Output is correct
17 Execution timed out 3050 ms 47812 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 23868 KB Output is correct
3 Correct 14 ms 23892 KB Output is correct
4 Correct 18 ms 24020 KB Output is correct
5 Correct 24 ms 24020 KB Output is correct
6 Correct 20 ms 23892 KB Output is correct
7 Correct 24 ms 24020 KB Output is correct
8 Correct 21 ms 24020 KB Output is correct
9 Correct 15 ms 23896 KB Output is correct
10 Correct 16 ms 23892 KB Output is correct
11 Correct 137 ms 34248 KB Output is correct
12 Correct 159 ms 35008 KB Output is correct
13 Correct 184 ms 36416 KB Output is correct
14 Correct 268 ms 39100 KB Output is correct
15 Correct 367 ms 40052 KB Output is correct
16 Correct 404 ms 45992 KB Output is correct
17 Execution timed out 3050 ms 47812 KB Time limit exceeded
18 Halted 0 ms 0 KB -