Submission #897121

#	Time	Username	Problem	Language	Result	Execution time	Memory
897121		shmax	Pipes (CEOI15_pipes)	C++14	0 / 100	1311 ms	65536 KiB

pipes

/*
 * powered by ANDRIY POPYK
 * in honor of MYSELF and SEGMENT DECOMPOSITION and N^(log(N)) and (Harry Potter and the Methods of Rationality) and Monkie D. Luffy
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

//#pragma GCC optimize("O3")
//#pragma GCC target("avx,avx2,fma")
//#pragma GCC optimization ("unroll-loops")
//#pragma GCC target("avx,avx2,sse,sse2,sse3,sse4,popcnt")

using namespace std;
using namespace __gnu_pbds;
//#define int long long
#define float long double
#define elif else if
#define endl "\n"
#define mod 1000000007
#define pi acos(-1)
#define eps 0.000000001
#define inf 1000'000'000'000'000'000LL
#define FIXED(a) cout << fixed << setprecision(a)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define time_init auto start = std::chrono::high_resolution_clock::now()
#define time_report                                       \
    auto end = std::chrono::high_resolution_clock::now(); \
    std::cout << std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count() << " ms" << endl
#define debug(x) \
    { cerr << #x << " = " << x << endl; }
#define len(x) (int) x.size()
#define sqr(x) ((x) * (x))
#define cube(x) ((x) * (x) * (x))
#define bit(x, i) (((x) >> (i)) & 1)
#define set_bit(x, i) ((x) | (1LL << (i)))
#define clear_bit(x, i) ((x) & (~(1LL << (i))))
#define toggle_bit(x, i) ((x) ^ (1LL << (i)))
#define low_bit(x) ((x) & (-(x)))
#define count_bit(x) __builtin_popcountll(x)
#define srt(x) sort(all(x))
#define rsrt(x) sort(rall(x))
#define mp make_pair
#define maxel(x) (*max_element(all(x)))
#define minel(x) (*min_element(all(x)))
#define maxelpos(x) (max_element(all(x)) - x.begin())
#define minelpos(x) (min_element(all(x)) - x.begin())
#define sum(x) (accumulate(all(x), 0LL))
#define product(x) (accumulate(all(x), 1LL, multiplies<int>()))
#define gcd __gcd
#define lcm(a, b) ((a) / gcd(a, b) * (b))
#define rev(x) (reverse(all(x)))
#define shift_left(x, k) (rotate(x.begin(), x.begin() + k, x.end()))
#define shift_right(x, k) (rotate(x.rbegin(), x.rbegin() + k, x.rend()))
#define is_sorted(x) (is_sorted_until(all(x)) == x.end())
#define is_even(x) (((x) &1) == 0)
#define is_odd(x) (((x) &1) == 1)
#define pow2(x) (1LL << (x))

struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

template<typename T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;
template<typename T>
using max_heap = priority_queue<T, vector<T>, less<T>>;
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T>
using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T>
using matrix = vector<vector<T>>;
template<typename T>
using graph = vector<vector<T>>;
using hashmap = gp_hash_table<int, int, custom_hash>;

template<typename T>
vector<T> vect(int n, T val) {
    return vector<T>(n, val);
}

template<typename T>
vector<vector<T>> vect(int n, int m, T val) {
    return vector<vector<T>>(n, vector<T>(m, val));
}

template<typename T>
vector<vector<vector<T>>> vect(int n, int m, int k, T val) {
    return vector<vector<vector<T>>>(n, vector<vector<T>>(m, vector<T>(k, val)));
}

template<typename T>
vector<vector<vector<vector<T>>>> vect(int n, int m, int k, int l, T val) {
    return vector<vector<vector<vector<T>>>>(n, vector<vector<vector<T>>>(m, vector<vector<T>>(k, vector<T>(l, val))));
}

template<typename T>
matrix<T> new_matrix(int n, int m, T val) {
    return matrix<T>(n, vector<T>(m, val));
}

template<typename T>
graph<T> new_graph(int n) {
    return graph<T>(n);
}

template<class T, class S>
inline bool chmax(T &a, const S &b) {
    return (a < b ? a = b, 1 : 0);
}

template<class T, class S>
inline bool chmin(T &a, const S &b) {
    return (a > b ? a = b, 1 : 0);
}

using i8 = int8_t;
using i16 = int16_t;
using i32 = int32_t;
using i64 = int64_t;
using i128 = __int128_t;
using u8 = uint8_t;
using u16 = uint16_t;
using u32 = uint32_t;
using u64 = uint64_t;
using u128 = __uint128_t;

template<typename T>
using vec = vector<T>;

using pII = pair<int, int>;
template<typename T>
using enumerated = pair<T, int>;

struct Bridges {
private:
    graph<pair<int, int>> g;
    vector<int> tin, fup;
    vector<bool> used;
    int timer;


    void build_dfs(int v, int p = -1, int edge_idx = -1) {
        used[v] = true;
        tin[v] = fup[v] = timer++;
        for (auto [u, id]: g[v]) {
            if (u == p) {
                continue;
            }
            if (used[u]) {
                fup[v] = min(fup[v], tin[u]);
            } else {
                build_dfs(u, v, id);
                fup[v] = min(fup[v], fup[u]);
            }
        }
        if (p != -1 and fup[v] > tin[p]) {
            is_bridge[edge_idx] = true;
        }
    }


public:
    vec<bool> is_bridge;
    vec<pair<int, int>> edges;


    Bridges(graph<int> &gt) {
        for (int i = 0; i < len(gt); ++i) {
            for (auto &to: gt[i]) {
                if (i < to) {
                    edges.emplace_back(i, to);
                }
            }
        }
        g = graph<pair<int, int>>(len(gt));
        int idx = 0;
        for (auto &edge: edges) {
            g[edge.first].emplace_back(edge.second, idx);
            g[edge.second].emplace_back(edge.first, idx);
            ++idx;
        }
        tin = fup = vector<int>(len(g));
        used = vector<bool>(len(g));
        timer = 0;
        is_bridge = vec<bool>(idx);
        for (int i = 0; i < len(g); ++i) {
            if (!used[i]) {
                build_dfs(i);
            }
        }
    }

    void print() {
        for (int i = 0; i < len(edges); ++i) {
            if (is_bridge[i]) {
                cout << edges[i].first + 1 << " " << edges[i].second + 1 << endl;
            }
        }
    }

};


signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int n, m;
    cin >> n >> m;
    graph<int> g(n);
    for (int i = 0; i < m; ++i) {
        int v, u;
        cin >> v >> u;
        --v, --u;
        g[v].emplace_back(u);
        g[u].emplace_back(v);
    }
    Bridges bridges(g);
    bridges.print();
}

Compilation message (stderr)

pipes.cpp: In member function 'void Bridges::build_dfs(int, int, int)':
pipes.cpp:158:19: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
  158 |         for (auto [u, id]: g[v]) {
      |                   ^

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
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• Subtask 10: 0 / 10