結果
問題 | No.1553 Lovely City |
ユーザー |
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提出日時 | 2021-06-19 15:31:57 |
言語 | C++17 (gcc 13.3.0 + boost 1.87.0) |
結果 |
AC
|
実行時間 | 190 ms / 2,000 ms |
コード長 | 10,131 bytes |
コンパイル時間 | 2,786 ms |
コンパイル使用メモリ | 217,456 KB |
最終ジャッジ日時 | 2025-01-22 10:03:21 |
ジャッジサーバーID (参考情報) |
judge2 / judge4 |
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ファイルパターン | 結果 |
---|---|
sample | AC * 2 |
other | AC * 26 |
ソースコード
// >>> TEMPLATES#include <bits/stdc++.h>using namespace std;using ll = long long;using ld = long double;using i32 = int32_t;using i64 = int64_t;using u32 = uint32_t;using u64 = uint64_t;#define int ll#define rep(i, n) for (int i = 0; i < (int)(n); i++)#define rep1(i, n) for (int i = 1; i <= (int)(n); i++)#define repR(i, n) for (int i = (int)(n)-1; i >= 0; i--)#define rep1R(i, n) for (int i = (int)(n); i >= 1; i--)#define loop(i, a, B) for (int i = a; i B; i++)#define loopR(i, a, B) for (int i = a; i B; i--)#define all(x) begin(x), end(x)#define allR(x) rbegin(x), rend(x)#define rng(x, l, r) begin(x) + (l), begin(x) + (r)#define pb push_back#define eb emplace_back#define fst first#define snd secondtemplate <class A, class B> constexpr auto mp(A &&a, B &&b) { return make_pair(forward<A>(a), forward<B>(b)); }template <class... T> constexpr auto mt(T&&... x) { return make_tuple(forward<T>(x)...); }template <class Int> auto constexpr inf_ = numeric_limits<Int>::max()/2-1;auto constexpr INF32 = inf_<int32_t>;auto constexpr INF64 = inf_<int64_t>;auto constexpr INF = inf_<int>;#ifdef LOCAL#include "debug.hpp"#else#define dump(...) (void)(0)#define say(x) (void)(0)#define debug if (0)#endiftemplate <class T, class Comp> struct pque : priority_queue<T, vector<T>, Comp> { vector<T> &data() { return this->c; } void clear() { this->c.clear(); } };template <class T> using pque_max = pque<T, less<T>>;template <class T> using pque_min = pque<T, greater<T>>;template <class T, class = typename T::iterator, enable_if_t<!is_same<T, string>::value, int> = 0>ostream& operator<<(ostream& os, T const& a) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }template <class T, size_t N, enable_if_t<!is_same<T, char>::value, int> = 0>ostream& operator<<(ostream& os, const T (&a)[N]) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }template <class T, class = decltype(begin(declval<T&>())), class = typename enable_if<!is_same<T, string>::value>::type>istream& operator>>(istream& is, T &a) { for (auto& x : a) is >> x; return is; }template <class T, class S> ostream& operator<<(ostream& os, pair<T, S> const& p) { return os << p.first << " " << p.second; }template <class T, class S> istream& operator>>(istream& is, pair<T, S>& p) { return is >> p.first >> p.second; }struct IOSetup { IOSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); } } iosetup;template <class F> struct FixPoint : private F {constexpr FixPoint(F&& f) : F(forward<F>(f)) {}template <class... T> constexpr auto operator()(T&&... x) const { return F::operator()(*this, forward<T>(x)...); }};struct MakeFixPoint { template <class F> constexpr auto operator|(F&& f) const { return FixPoint<F>(forward<F>(f)); } };#define MFP MakeFixPoint()|#define def(name, ...) auto name = MFP [&](auto &&name, __VA_ARGS__)template <class T, size_t d> struct vec_impl {using type = vector<typename vec_impl<T, d-1>::type>;template <class... U> static type make_v(size_t n, U&&... x) { return type(n, vec_impl<T, d-1>::make_v(forward<U>(x)...)); }};template <class T> struct vec_impl<T, 0> { using type = T; static type make_v(T const& x = {}) { return x; } };template <class T, size_t d = 1> using vec = typename vec_impl<T, d>::type;template <class T, size_t d = 1, class... Args> auto make_v(Args&&... args) { return vec_impl<T, d>::make_v(forward<Args>(args)...); }template <class T> void quit(T const& x) { cout << x << endl; exit(0); }template <class T, class U> constexpr bool chmin(T& x, U const& y) { if (x > (T)y) { x = (T)y; return true; } return false; }template <class T, class U> constexpr bool chmax(T& x, U const& y) { if (x < (T)y) { x = (T)y; return true; } return false; }template <class It> constexpr auto sumof(It b, It e) { return accumulate(b, e, typename iterator_traits<It>::value_type{}); }template <class T> int sz(T const& x) { return x.size(); }template <class C, class T> int lbd(C const& v, T const& x) { return lower_bound(begin(v), end(v), x)-begin(v); }template <class C, class T> int ubd(C const& v, T const& x) { return upper_bound(begin(v), end(v), x)-begin(v); }constexpr int64_t mod(int64_t x, int64_t m) { assert(m > 0); return (x %= m) < 0 ? x+m : x; }constexpr int64_t div_floor(int64_t x, int64_t y) { assert(y != 0); return x/y - ((x^y) < 0 and x%y); }constexpr int64_t div_ceil(int64_t x, int64_t y) { assert(y != 0); return x/y + ((x^y) > 0 and x%y); }constexpr int dx[] = { 1, 0, -1, 0, 1, -1, -1, 1 };constexpr int dy[] = { 0, 1, 0, -1, 1, 1, -1, -1 };constexpr int popcnt(ll x) { return __builtin_popcountll(x); }mt19937_64 seed_{random_device{}()};template <class Int> Int rand(Int a, Int b) { return uniform_int_distribution<Int>(a, b)(seed_); }i64 irand(i64 a, i64 b) { return rand<i64>(a, b); } // [a, b]u64 urand(u64 a, u64 b) { return rand<u64>(a, b); } //template <class It> void shuffle(It l, It r) { shuffle(l, r, seed_); }template <class T> vector<T> &operator--(vector<T> &v) { for (T &x : v) --x; return v; }template <class T> vector<T> &operator++(vector<T> &v) { for (T &x : v) ++x; return v; }// <<<// >>> union findstruct UnionFind {int n, sz; // id : 0...n-1vector<int32_t> par;UnionFind(int n = 0) : n(n), sz(n), par(n, -1) { }void clear() {rep (i, n) par[i] = -1;sz = n;}int root(int x) {assert(0 <= x); assert(x < n);return par[x] < 0 ? x : par[x] = root(par[x]);}bool unite(int x, int y) {x = root(x), y = root(y);if (x == y) return false;sz--;if (par[x] < par[y]) swap(x, y);par[y] += par[x];par[x] = y;return true;}bool same(int x, int y) { return root(x) == root(y); }int size(int x) { return -par[root(x)]; }int size() const { return sz; }vector<vector<int32_t>> groups() {vector<vector<int32_t>> g(n);rep (i, n) if (par[i] < 0) g[i].reserve(-par[i]);rep (i, n) g[root(i)].push_back(i);vector<vector<int32_t>> grp; grp.reserve(size());rep (i, n) if (g[i].size()) grp.emplace_back(move(g[i]));return grp;}};// <<<// >>> scc#ifndef EDGE_INFO#define EDGE_INFOconstexpr int dest(int v) { return v; }template <class E, class = decltype(declval<E>().to)>constexpr int dest(E const& e) { return e.to; }constexpr int cost(int) { return 1; }template <class E, class = decltype(declval<E>().cost)>constexpr auto cost(E const& e) { return e.cost; }template <class E> using cost_t = decltype(cost(declval<E>()));#endiftemplate <class E> struct SCC {vector<vector<E>> const& g;vector<int32_t> ord, low, st;int32_t time = 0, pos = 0, sz = 0;SCC(vector<vector<E>> const& g) : g(g), ord(g.size()), low(g.size()), st(g.size()) {rep (v, g.size()) if (ord[v] == 0) dfs(v);for (auto &x : ord) x += sz;}void dfs(int32_t v) {low[v] = ord[v] = ++time; st[pos++] = v;for (auto const& e : g[v]) {if (ord[dest(e)] == 0) {dfs(dest(e));chmin(low[v], low[dest(e)]);} else if (ord[dest(e)] > 0) {chmin(low[v], ord[dest(e)]);}}if (low[v] == ord[v]) {sz++; do ord[st[--pos]] = -sz; while (st[pos] != v);}}// t-sorted idint id(int v) const { return ord[v]; }int size() const { return sz; }vector<vector<int>> groups() const {vector<vector<int>> grp(sz);rep (v, g.size()) grp[ord[v]].push_back(v);return grp;}// no multiple edges, no self-loops// no edge informationvector<vector<int>> graph() const {vector<vector<int>> ret(size());vector<int32_t> last(g.size(), -1);rep (v, g.size()) {for (auto const& e : g[v]) {const int32_t x = id(v), y = id(dest(e));if (x == y or last[y] == x) continue;last[y] = x;ret[x].push_back(y);}}return ret;}};template <class E> auto get_scc(vector<vector<E>> const& g) { return SCC<E>(g); }// <<<// >>> bfs#ifndef EDGE_INFO#define EDGE_INFOconstexpr int dest(int v) { return v; }template <class E, class = decltype(declval<E>().to)>constexpr int dest(E const& e) { return e.to; }constexpr int cost(int) { return 1; }template <class E, class = decltype(declval<E>().cost)>constexpr auto cost(E const& e) { return e.cost; }template <class E> using cost_t = decltype(cost(declval<E>()));#endiftemplate <class E>vector<int> bfs(vector<vector<E>> const& g, int s, int inf) {vector<int> d(g.size(), inf);queue<int> q;d[s] = 0;q.push(s);while (q.size()) {int x = q.front(); q.pop();for (auto const& e : g[x]) {const int y = dest(e);if (chmin(d[y], d[x]+1)) q.push(y);}}return d;}// <<<int32_t main() {int n, m; cin >> n >> m;vector<vector<int>> g(n);UnionFind uf(n);rep (i, m) {int x, y; cin >> x >> y; --x, --y;g[x].eb(y);uf.unite(x, y);}vector<pair<int, int>> es;auto scc = get_scc(g);auto grp = uf.groups();for (auto &v : grp) {sort(all(v), [&](int x, int y) { return scc.id(x) < scc.id(y); });bool found = false;rep (i, v.size()-1) {int x = v[i], y = v[i+1];es.eb(x, y);if (scc.id(x) == scc.id(y)) found = true;}if (found) {int x = v.back(), y = v.front();es.eb(x, y);}}cout << es.size() << '\n';for (auto [x, y] : es) cout << x+1 << " " << y+1 << '\n';debug {vector<vector<int>> h(n);for (auto [x, y] : es) h[x].eb(y);rep (x, n) {for (int y : g[x]) {auto d = bfs(h, x, INF);assert(d[y] < INF);}}}}