noya2_Library

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View the Project on GitHub noya2ruler/noya2_Library

:heavy_check_mark: test/data_structure/Cycle_Detection_Undirected_vector2d.test.cpp

Depends on

Code

#define PROBLEM "https://judge.yosupo.jp/problem/cycle_detection_undirected"

#include"../../template/template.hpp"
#include"../../data_structure/vector2d.hpp"

int main(){
    int n, m; in(n,m);
    vector2d<pii> g(n,m*2);
    rep(i,m){
        int u, v; in(u,v);
        g.add(u,pii(v,i));
        g.add(v,pii(u,i));
    }
    vector<bool> used(m,false), visited(n,false);
    queue<int> que;
    int sv = -1, tv = -1, eid = -1;
    rep(i,n){
        if (visited[i]) continue;
        que.push(i);
        visited[i] = true;
        while (!que.empty()){
            int p = que.front(); que.pop();
            for (auto [q, e] : g[p]){
                if (used[e]) continue;
                if (visited[q]){
                    sv = p, tv = q, eid = e;
                    continue;
                }
                used[e] = true;
                visited[q] = true;
                que.push(q);
            }
        }
    }
    if (sv == -1){
        cout << -1 << endl;
        return 0;
    }
    fill(all(visited),false);
    vector<int> vs, es;
    bool done = false;
    auto dfs = [&](auto sfs, int v) -> void {
        if (done) return ;
        vs.push_back(v);
        visited[v] = true;
        if (v == tv){
            done = true;
            return ;
        }
        for (auto [u, e] : g[v]){
            if (e == eid) continue;
            if (visited[u]) continue;
            es.push_back(e);
            sfs(sfs,u);
            if (done) return ;
            es.pop_back();
        }
        vs.pop_back();
    };
    dfs(dfs,sv);
    es.push_back(eid);
    out(vs.size());
    out(vs);
    out(es);
}
#line 1 "test/data_structure/Cycle_Detection_Undirected_vector2d.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/cycle_detection_undirected"

#line 2 "template/template.hpp"
using namespace std;

#include<bits/stdc++.h>
#line 1 "template/inout_old.hpp"
namespace noya2 {

template <typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &p){
    os << p.first << " " << p.second;
    return os;
}
template <typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &p){
    is >> p.first >> p.second;
    return is;
}

template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v){
    int s = (int)v.size();
    for (int i = 0; i < s; i++) os << (i ? " " : "") << v[i];
    return os;
}
template <typename T>
istream &operator>>(istream &is, vector<T> &v){
    for (auto &x : v) is >> x;
    return is;
}

void in() {}
template <typename T, class... U>
void in(T &t, U &...u){
    cin >> t;
    in(u...);
}

void out() { cout << "\n"; }
template <typename T, class... U, char sep = ' '>
void out(const T &t, const U &...u){
    cout << t;
    if (sizeof...(u)) cout << sep;
    out(u...);
}

template<typename T>
void out(const vector<vector<T>> &vv){
    int s = (int)vv.size();
    for (int i = 0; i < s; i++) out(vv[i]);
}

struct IoSetup {
    IoSetup(){
        cin.tie(nullptr);
        ios::sync_with_stdio(false);
        cout << fixed << setprecision(15);
        cerr << fixed << setprecision(7);
    }
} iosetup_noya2;

} // namespace noya2
#line 1 "template/const.hpp"
namespace noya2{

const int iinf = 1'000'000'007;
const long long linf = 2'000'000'000'000'000'000LL;
const long long mod998 =  998244353;
const long long mod107 = 1000000007;
const long double pi = 3.14159265358979323;
const vector<int> dx = {0,1,0,-1,1,1,-1,-1};
const vector<int> dy = {1,0,-1,0,1,-1,-1,1};
const string ALP = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const string alp = "abcdefghijklmnopqrstuvwxyz";
const string NUM = "0123456789";

void yes(){ cout << "Yes\n"; }
void no(){ cout << "No\n"; }
void YES(){ cout << "YES\n"; }
void NO(){ cout << "NO\n"; }
void yn(bool t){ t ? yes() : no(); }
void YN(bool t){ t ? YES() : NO(); }

} // namespace noya2
#line 2 "template/utils.hpp"

#line 6 "template/utils.hpp"

namespace noya2{

unsigned long long inner_binary_gcd(unsigned long long a, unsigned long long b){
    if (a == 0 || b == 0) return a + b;
    int n = __builtin_ctzll(a); a >>= n;
    int m = __builtin_ctzll(b); b >>= m;
    while (a != b) {
        int mm = __builtin_ctzll(a - b);
        bool f = a > b;
        unsigned long long c = f ? a : b;
        b = f ? b : a;
        a = (c - b) >> mm;
    }
    return a << std::min(n, m);
}

template<typename T> T gcd_fast(T a, T b){ return static_cast<T>(inner_binary_gcd(std::abs(a),std::abs(b))); }

long long sqrt_fast(long long n) {
    if (n <= 0) return 0;
    long long x = sqrt(n);
    while ((x + 1) * (x + 1) <= n) x++;
    while (x * x > n) x--;
    return x;
}

template<typename T> T floor_div(const T n, const T d) {
    assert(d != 0);
    return n / d - static_cast<T>((n ^ d) < 0 && n % d != 0);
}

template<typename T> T ceil_div(const T n, const T d) {
    assert(d != 0);
    return n / d + static_cast<T>((n ^ d) >= 0 && n % d != 0);
}

template<typename T> void uniq(std::vector<T> &v){
    std::sort(v.begin(),v.end());
    v.erase(unique(v.begin(),v.end()),v.end());
}

template <typename T, typename U> inline bool chmin(T &x, U y) { return (y < x) ? (x = y, true) : false; }

template <typename T, typename U> inline bool chmax(T &x, U y) { return (x < y) ? (x = y, true) : false; }

template<typename T> inline bool range(T l, T x, T r){ return l <= x && x < r; }

} // namespace noya2
#line 8 "template/template.hpp"

#define rep(i,n) for (int i = 0; i < (int)(n); i++)
#define repp(i,m,n) for (int i = (m); i < (int)(n); i++)
#define reb(i,n) for (int i = (int)(n-1); i >= 0; i--)
#define all(v) (v).begin(),(v).end()

using ll = long long;
using ld = long double;
using uint = unsigned int;
using ull = unsigned long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
using pil = pair<int,ll>;
using pli = pair<ll,int>;

namespace noya2{

/*　~ (. _________ . /)　*/

}

using namespace noya2;


#line 2 "data_structure/vector2d.hpp"

#line 4 "data_structure/vector2d.hpp"
#include<ranges>

namespace noya2{

template<class E>
struct vector2d {
    vector2d (int n_ = 0, int m_ = 0) : n(n_), m(m_), inner_element_id(0) {
        es.resize(m);
        start.resize(m,0);
        if (m == 0) build();
    }
    void add(int from, E e){
        es[inner_element_id] = e, start[inner_element_id] = from;
        if (++inner_element_id == m) build();
    }
    const auto operator[](int idx){ return std::ranges::subrange(es.begin()+start[idx],es.begin()+start[idx+1]); }
    std::vector<int> start;
  private:
    void build(){
        std::vector<E> nes(m);
        std::vector<int> nstart(n+1,0);
        for (int i = 0; i < m; i++) nstart[start[i]+1]++;
        for (int i = 0; i < n; i++) nstart[i+1] += nstart[i];
        auto geta = nstart;
        for (int i = 0; i < m; i++) nes[geta[start[i]]++] = es[i];
        std::swap(nes,es); std::swap(nstart,start);
    }
    int n, m, inner_element_id;
    std::vector<E> es;
};

} // namespace noya2
#line 5 "test/data_structure/Cycle_Detection_Undirected_vector2d.test.cpp"

int main(){
    int n, m; in(n,m);
    vector2d<pii> g(n,m*2);
    rep(i,m){
        int u, v; in(u,v);
        g.add(u,pii(v,i));
        g.add(v,pii(u,i));
    }
    vector<bool> used(m,false), visited(n,false);
    queue<int> que;
    int sv = -1, tv = -1, eid = -1;
    rep(i,n){
        if (visited[i]) continue;
        que.push(i);
        visited[i] = true;
        while (!que.empty()){
            int p = que.front(); que.pop();
            for (auto [q, e] : g[p]){
                if (used[e]) continue;
                if (visited[q]){
                    sv = p, tv = q, eid = e;
                    continue;
                }
                used[e] = true;
                visited[q] = true;
                que.push(q);
            }
        }
    }
    if (sv == -1){
        cout << -1 << endl;
        return 0;
    }
    fill(all(visited),false);
    vector<int> vs, es;
    bool done = false;
    auto dfs = [&](auto sfs, int v) -> void {
        if (done) return ;
        vs.push_back(v);
        visited[v] = true;
        if (v == tv){
            done = true;
            return ;
        }
        for (auto [u, e] : g[v]){
            if (e == eid) continue;
            if (visited[u]) continue;
            es.push_back(e);
            sfs(sfs,u);
            if (done) return ;
            es.pop_back();
        }
        vs.pop_back();
    };
    dfs(dfs,sv);
    es.push_back(eid);
    out(vs.size());
    out(vs);
    out(es);
}
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