結果

問題 No.1254 補強への架け橋
ユーザー ecottea
提出日時 2022-11-09 00:56:35
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 76 ms / 2,000 ms
コード長 8,447 bytes
コンパイル時間 3,710 ms
コンパイル使用メモリ 236,860 KB
実行使用メモリ 20,144 KB
最終ジャッジ日時 2024-07-22 08:30:40
合計ジャッジ時間 13,172 ms
ジャッジサーバーID
(参考情報)
judge4 / judge2
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 123
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#ifndef HIDDEN_IN_VS //
//
#define _CRT_SECURE_NO_WARNINGS
//
#include <bits/stdc++.h>
using namespace std;
//
using ll = long long; // -2^63 2^63 = 9 * 10^18int -2^31 2^31 = 2 * 10^9
using pii = pair<int, int>; using pll = pair<ll, ll>; using pil = pair<int, ll>; using pli = pair<ll, int>;
using vi = vector<int>; using vvi = vector<vi>; using vvvi = vector<vvi>;
using vl = vector<ll>; using vvl = vector<vl>; using vvvl = vector<vvl>;
using vb = vector<bool>; using vvb = vector<vb>; using vvvb = vector<vvb>;
using vc = vector<char>; using vvc = vector<vc>; using vvvc = vector<vvc>;
using vd = vector<double>; using vvd = vector<vd>; using vvvd = vector<vvd>;
template <class T> using priority_queue_rev = priority_queue<T, vector<T>, greater<T>>;
using Graph = vvi;
//
const double PI = acos(-1);
const vi DX = { 1, 0, -1, 0 }; // 4
const vi DY = { 0, 1, 0, -1 };
int INF = 1001001001; ll INFL = 4004004004004004004LL;
double EPS = 1e-12;
//
struct fast_io { fast_io() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(18); } } fastIOtmp;
//
#define all(a) (a).begin(), (a).end()
#define sz(x) ((int)(x).size())
#define lbpos(a, x) (int)distance((a).begin(), std::lower_bound(all(a), x))
#define ubpos(a, x) (int)distance((a).begin(), std::upper_bound(all(a), x))
#define Yes(b) {cout << ((b) ? "Yes\n" : "No\n");}
#define rep(i, n) for(int i = 0, i##_len = int(n); i < i##_len; ++i) // 0 n-1
#define repi(i, s, t) for(int i = int(s), i##_end = int(t); i <= i##_end; ++i) // s t
#define repir(i, s, t) for(int i = int(s), i##_end = int(t); i >= i##_end; --i) // s t
#define repe(v, a) for(const auto& v : (a)) // a
#define repea(v, a) for(auto& v : (a)) // a
#define repb(set, d) for(int set = 0; set < (1 << int(d)); ++set) // d
#define repp(a) sort(all(a)); for(bool a##_perm = true; a##_perm; a##_perm = next_permutation(all(a))) // a
#define smod(n, m) ((((n) % (m)) + (m)) % (m)) // mod
#define uniq(a) {sort(all(a)); (a).erase(unique(all(a)), (a).end());} //
#define EXIT(a) {cout << (a) << endl; exit(0);} //
//
template <class T> inline ll pow(T n, int k) { ll v = 1; rep(i, k) v *= n; return v; }
template <class T> inline bool chmax(T& M, const T& x) { if (M < x) { M = x; return true; } return false; } // true
    
template <class T> inline bool chmin(T& m, const T& x) { if (m > x) { m = x; return true; } return false; } // true
    
//
template <class T, class U> inline istream& operator>>(istream& is, pair<T, U>& p) { is >> p.first >> p.second; return is; }
template <class T> inline istream& operator>>(istream& is, vector<T>& v) { repea(x, v) is >> x; return is; }
template <class T> inline vector<T>& operator--(vector<T>& v) { repea(x, v) --x; return v; }
template <class T> inline vector<T>& operator++(vector<T>& v) { repea(x, v) ++x; return v; }
// Visual Studio
#ifdef _MSC_VER
#include "local.hpp"
// gcc
#else
inline int popcount(int n) { return __builtin_popcount(n); }
inline int popcount(ll n) { return __builtin_popcountll(n); }
inline int lsb(int n) { return n != 0 ? __builtin_ctz(n) : -1; }
inline int lsb(ll n) { return n != 0 ? __builtin_ctzll(n) : -1; }
inline int msb(int n) { return n != 0 ? (31 - __builtin_clz(n)) : -1; }
inline int msb(ll n) { return n != 0 ? (63 - __builtin_clzll(n)) : -1; }
#define gcd __gcd
#define dump(...)
#define dumpel(v)
#define dump_list(v)
#define input_from_file(f)
#define output_to_file(f)
#define Assert(b) { if (!(b)) while (1) cout << "OLE"; }
#endif
#endif //
//--------------AtCoder --------------
#include <atcoder/all>
using namespace atcoder;
//using mint = modint1000000007;
using mint = modint998244353;
//using mint = modint; // mint::set_mod(m);
istream& operator>>(istream& is, mint& x) { ll x_; is >> x_; x = x_; return is; }
ostream& operator<<(ostream& os, const mint& x) { os << x.val(); return os; }
using vm = vector<mint>; using vvm = vector<vm>; using vvvm = vector<vvm>;
//----------------------------------------
//
/*
* to :
* id :
*/
struct IEdge {
// verify : https://atcoder.jp/contests/arc143/tasks/arc143_d
int to; //
int id; //
bool dir; //
IEdge() : to(-1), id(-1), dir(true) {}
IEdge(int to, int id, bool dir) : to(to), id(id), dir(dir) {}
//
operator int() const { return to; }
#ifdef _MSC_VER
friend ostream& operator<<(ostream& os, const IEdge& e) {
os << '(' << "to:" << e.to << ',' << "id:" << e.id << ',' << (e.dir ? "fwd" : "rev") << ')';
return os;
}
#endif
};
//
/*
* IGraph g
* g[v] : v
*
* verify : https://atcoder.jp/contests/arc143/tasks/arc143_d
*/
using IGraph = vector<vector<IEdge>>;
//O(|V| + |E|)
/*
* n m
*
* n :
* m :
* g :
* undirected : true
* one_indexed : 1-indexed true
*/
void read_graph(int n, int m, IGraph& g, bool undirected = true, bool one_indexed = true) {
g = IGraph(n);
rep(i, m) {
int a, b;
cin >> a >> b;
if (one_indexed) { a--; b--; }
g[a].push_back({ b, i, true });
if (undirected) g[b].push_back({ a, i, false });
}
}
//O(|V| + |E|)
/*
* g vs es -1
* vs[0] vs[1] es[0]
*/
template <class E> int cycle_detection(const vector<vector<E>>& g, vi& vs, vector<E>* es = nullptr) {
// verify : https://yukicoder.me/problems/no/1254
int n = sz(g);
vb seen(n);
vs.clear();
if (es != nullptr) es->clear();
// s : p :
// : -1: -2:
function<int(int, int)> dfs = [&](int s, int p) {
// 辿
if (seen[s]) {
vs.push_back(s);
return s;
}
seen[s] = true;
// s 辿 t
repe(t, g[s]) {
// 2
if (t == p) continue;
// t
auto end = dfs(t, s);
// t
if (end == -1) continue;
// s
if (end == s || end == -2) {
if (es != nullptr && end == s) es->push_back(t);
return -2;
}
//
if (end >= 0) {
vs.push_back(s);
if (es != nullptr) es->push_back(t);
}
return end;
}
return -1;
};
// v
rep(v, n) {
//
if (seen[v]) continue;
// v
int end = dfs(v, v);
//
if (end != -1) {
if (es != nullptr) {
auto e = es->back();
es->pop_back();
reverse(all(vs));
reverse(all(*es));
es->push_back(e);
}
return sz(vs);
}
}
return -1;
}
int main() {
// input_from_file("input.txt");
// output_to_file("output.txt");
int n;
cin >> n;
IGraph g;
read_graph(n, n, g);
vi vs; vector<IEdge> es;
int k = cycle_detection(g, vs, &es);
dump(vs);dump(es);
cout << k << endl;
rep(i, k) cout << es[i].id + 1 << (i < k - 1 ? " " : "\n");
}
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