test/yosupo/bipartitematching.test.cpp

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• Last update: 2023-06-25 16:24:15+09:00
• Problem: https://judge.yosupo.jp/problem/bipartitematching

Depends on

• Fast IO library (basic/FastIO.hpp)
• basic/template.hpp
• Dinic's algorithm (graph/Dinic.hpp)

Code

#define PROBLEM "https://judge.yosupo.jp/problem/bipartitematching"
#include "../../basic/template.hpp"
#include "../../basic/FastIO.hpp"
#include "../../graph/Dinic.hpp"
FastIO::Scanner cin;
FastIO::Printer cout;
int L, R, M, a[200010], b[200010];
int main() {
	cin >> L >> R >> M;
	Dinic flow(L + R + 2);
	REP(i, L) flow.add_edge(0, i, 1);
	for (int i = L + 1; i <= L + R; i++) flow.add_edge(i, L + R + 1, 1);
	rep(i, M) {
		cin >> a[i] >> b[i];
		flow.add_edge(a[i] + 1, b[i] + L + 1, 1);
	}
	cout << flow.max_flow(0, L + R + 1) << '\n';
	auto vec = flow.restore();
	rep(i, M) {
		if (vec[i + L + R]) cout << a[i] << ' ' << b[i] << '\n';
	}
	return 0;
}

#line 1 "test/yosupo/bipartitematching.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/bipartitematching"
#line 2 "basic/template.hpp"
#define _CRT_SECURE_NO_WARNINGS
#ifndef __clang__
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#endif
#include <string.h>
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cfloat>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <memory>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#define rep(i, n) for (int i = 0; i < int(n); i++)
#define REP(i, n) for (int i = 1; i <= int(n); i++)
#define all(V) V.begin(), V.end()

using i128 = __int128_t;
using u128 = __uint128_t;
using uint = unsigned int;
using lint = long long;
using ulint = unsigned long long;
using IP = std::pair<int, int>;
using LP = std::pair<lint, lint>;

constexpr int INF = INT_MAX / 2;
constexpr lint LINF = LLONG_MAX / 2;
constexpr double eps = DBL_EPSILON * 10;
constexpr double PI = 3.141592653589793238462643383279;

template <class T>
class prique : public std::priority_queue<T, std::vector<T>, std::greater<T>> {};
int popcount(uint x) {
#if __cplusplus >= 202002L
	return std::popcount(x);
#else
#ifndef __clang__
	return __builtin_popcount(x);
#endif
#endif
	x = (x & 0x55555555) + (x >> 1 & 0x55555555);
	x = (x & 0x33333333) + (x >> 2 & 0x33333333);
	x = (x & 0x0f0f0f0f) + (x >> 4 & 0x0f0f0f0f);
	x = (x & 0x00ff00ff) + (x >> 8 & 0x00ff00ff);
	return (x & 0x0000ffff) + (x >> 16 & 0x0000ffff);
}
template <class F>
inline constexpr decltype(auto) lambda_fix(F&& f) {
	return [f = std::forward<F>(f)](auto&&... args) {
		return f(f, std::forward<decltype(args)>(args)...);
	};
}
template <class T>
constexpr std::vector<T> make_vec(size_t n) {
	return std::vector<T>(n);
}
template <class T, class... Args>
constexpr auto make_vec(size_t n, Args&&... args) {
	return std::vector<decltype(make_vec<T>(args...))>(n, make_vec<T>(std::forward<Args>(args)...));
}
template <class T, class U, class Stream>
Stream& operator>>(Stream& ist, std::pair<T, U>& x) {
	return ist >> x.first >> x.second;
}
template <class T, class U, class Stream>
Stream& operator<<(Stream& ost, const std::pair<T, U>& x) {
	return ost << x.first << " " << x.second;
}
template <class Container,
		  std::enable_if_t<!std::is_same<Container, std::string>::value, std::nullptr_t> = nullptr>
auto operator>>(std::istream& ist, Container& cont)
	-> decltype(typename Container::iterator(), std::cin)& {
	Container tmp;
	while (true) {
		typename Container::value_type t;
		ist >> t;
		tmp.emplace_back(t);
		if (getchar() == '\n') break;
	}
	cont = Container(std::move(tmp));
	return ist;
}
template <class Container, class Stream,
		  std::enable_if_t<!std::is_same<Container, std::string>::value, std::nullptr_t> = nullptr>
auto operator<<(Stream& ost, const Container& cont)
	-> decltype(typename Container::iterator(), ost)& {
	for (auto it = cont.begin(); it != cont.end(); it++) {
		if (it != cont.begin()) ost << ' ';
		ost << *it;
	}
	return ost;
}
template <class Container>
auto sum(const Container& cont) -> decltype(typename Container::iterator(), 0LL) {
	lint res = 0;
	for (auto it = cont.begin(); it != cont.end(); it++) res += *it;
	return res;
}
template <class T, class U>
constexpr inline bool chmax(T& lhs, const U& rhs) noexcept {
	if (lhs < rhs) {
		lhs = rhs;
		return true;
	}
	return false;
}
template <class T, class U>
constexpr inline bool chmin(T& lhs, const U& rhs) noexcept {
	if (lhs > rhs) {
		lhs = rhs;
		return true;
	}
	return false;
}
constexpr inline lint gcd(lint a, lint b) noexcept {
	while (b) {
		lint c = a;
		a = b;
		b = c % b;
	}
	return a;
}
inline lint lcm(lint a, lint b) noexcept { return a / gcd(a, b) * b; }
constexpr bool isprime(lint n) noexcept {
	if (n == 1) return false;
	for (int i = 2; i * i <= n; i++) {
		if (n % i == 0) return false;
	}
	return true;
}
template <class T>
constexpr T mypow(T a, lint b) noexcept {
	T res(1);
	while (true) {
		if (b & 1) res *= a;
		b >>= 1;
		if (!b) break;
		a *= a;
	}
	return res;
}
constexpr lint modpow(lint a, lint b, lint m) noexcept {
	a %= m;
	lint res(1);
	while (b) {
		if (b & 1) res *= a, res %= m;
		a *= a, a %= m, b >>= 1;
	}
	return res;
}
LP extGcd(lint a, lint b) noexcept {
	if (b == 0) return {1, 0};
	LP s = extGcd(b, a % b);
	std::swap(s.first, s.second);
	s.second -= a / b * s.first;
	return s;
}
LP ChineseRem(const lint& b1, const lint& m1, const lint& b2, const lint& m2) noexcept {
	auto p = extGcd(m1, m2);
	lint g = gcd(m1, m2), l = m1 / g * m2;
	lint tmp = (b2 - b1) / g * p.first % (m2 / g);
	lint r = (b1 + m1 * tmp + l) % l;
	return {r, l};
}
int LCS(const std::string& a, const std::string& b) {
	auto dp = make_vec<int>(a.size() + 1, b.size() + 1);
	rep(i, a.size()) {
		rep(j, b.size()) {
			chmax(dp[i + 1][j], dp[i][j]);
			chmax(dp[i][j + 1], dp[i][j]);
			if (a[i] == b[j]) chmax(dp[i + 1][j + 1], dp[i][j] + 1);
		}
		chmax(dp[i + 1][b.size()], dp[i][b.size()]);
	}
	rep(j, b.size()) chmax(dp[a.size()][j + 1], dp[a.size()][j]);
	return dp[a.size()][b.size()];
}
template <class T, std::enable_if_t<std::is_convertible<int, T>::value, std::nullptr_t> = nullptr>
void compress(std::vector<T>& vec) {
	auto tmp = vec;
	std::sort(all(tmp));
	tmp.erase(std::unique(all(tmp)), tmp.end());
	for (T& i : vec) i = std::lower_bound(all(tmp), i) - tmp.begin();
}
template <class T>
void compress(T* l, T* r) {
	std::vector<T> tmp(l, r);
	std::sort(all(tmp));
	tmp.erase(std::unique(all(tmp)), tmp.end());
	for (auto i = l; i < r; i++) {
		*i = std::lower_bound(all(tmp), *i) - tmp.begin();
	}
}
template <class InputIter>
void compress(InputIter l, InputIter r) {
	std::vector<typename InputIter::value_type> tmp(l, r);
	std::sort(all(tmp));
	tmp.erase(std::unique(all(tmp)), tmp.end());
	for (auto i = l; i < r; i++) {
		*i = std::lower_bound(all(tmp), *i) - tmp.begin();
	}
}
template <class InputIter,
		  std::enable_if_t<std::is_same<typename InputIter::value_type, std::pair<IP, int>>::value,
						   std::nullptr_t> = nullptr>
void mo_sort(InputIter l, InputIter r, int N) {
	const int M = std::max(1.0, std::sqrt(lint(N) * N / std::distance(l, r)));
	std::sort(l, r, [M](const auto& lhs, const auto& rhs) {
		if (lhs.first.first / M < rhs.first.first / M) return true;
		if (lhs.first.first / M == rhs.first.first / M) return lhs.first.second < rhs.first.second;
		return false;
	});
	int before = -1, cnt = 0;
	bool f = false;
	for (InputIter i = l; i != r; i++) {
		if (before != i->first.first / M) {
			if (f) std::reverse(i - cnt, i);
			f ^= true, before = i->first.first / M, cnt = 1;
		} else
			cnt++;
	}
	if (f) std::reverse(r - cnt, r);
}
template <class T>
std::vector<T> xor_bases(const std::vector<T>& vec) {
	std::vector<T> res;
	for (T i : vec) {
		for (T j : res) {
			chmin(i, i ^ j);
		}
		if (i) res.emplace_back(i);
	}
	return res;
}
#line 3 "basic/FastIO.hpp"
namespace FastIO {
	static constexpr size_t buf_size = 1 << 18;
	static constexpr size_t integer_size = 19;

	static char inbuf[buf_size + 1] = {};
	static char outbuf[buf_size + 1] = {};

	class Scanner {
		size_t pos = 0, end = buf_size;
		void load() {
			end = fread(inbuf, 1, buf_size, stdin);
			inbuf[end] = '\0';
		}
		void ignore_space() {
			while (inbuf[pos] <= ' ') {
				if (__builtin_expect(++pos == end, 0)) reload();
			}
		}
		char next() { return inbuf[pos++]; }
		char next_nonspace() {
			ignore_space();
			return inbuf[pos++];
		}

	  public:
		Scanner() { load(); }
		void reload() {
			size_t length = end - pos;
			memmove(inbuf, inbuf + pos, length);
			end = length + fread(inbuf + length, 1, buf_size - length, stdin);
			inbuf[end] = '\0';
			pos = 0;
		}
		void scan() {}
		void scan(char& c) { c = next_nonspace(); }
		void scan(std::string& s) {
			ignore_space();
			s = "";
			do {
				size_t start = pos;
				while (inbuf[pos] > ' ') pos++;
				s += std::string(inbuf + start, inbuf + pos);
				if (inbuf[pos] != '\0') break;
				reload();
			} while (true);
		}
		template <typename T, std::enable_if_t<std::is_integral_v<T>, std::nullptr_t> = nullptr>
		void scan(T& x) {
			char c = next_nonspace();
			if (__builtin_expect(pos + integer_size >= end, 0)) reload();
			bool minus = false;
			if (c == '-')
				minus = true, x = 0;
			else
				x = c & 15;
			while ((c = next()) >= '0') x = x * 10 + (c & 15);
			if (minus) x = -x;
		}
		template <typename T, class... Args>
		void scan(T& x, Args&... args) {
			scan(x);
			scan(args...);
		}
		template <typename T,
				  std::enable_if_t<std::is_same_v<T, char> || std::is_same_v<T, std::string> ||
									   std::is_integral_v<T>,
								   std::nullptr_t> = nullptr>
		Scanner& operator>>(T& x) {
			scan(x);
			return *this;
		}
	};

	class Printer {
		static constexpr size_t block_size = 10000;
		static const std::unique_ptr<char[]> block_str;
		size_t pos = 0;

		static constexpr lint powers[] = {1,
										  10,
										  100,
										  1000,
										  10000,
										  100000,
										  1000000,
										  10000000,
										  100000000,
										  1000000000,
										  10000000000,
										  100000000000,
										  1000000000000,
										  10000000000000,
										  100000000000000,
										  1000000000000000,
										  10000000000000000,
										  100000000000000000,
										  1000000000000000000};

		static std::unique_ptr<char[]> precompute() {
			std::unique_ptr<char[]> res(new char[block_size * 4]);
			rep(i, block_size) {
				size_t j = 4, k = i;
				while (j--) {
					res[i * 4 + j] = k % 10 + '0';
					k /= 10;
				}
			}
			return res;
		}
		template <typename T>
		size_t integer_digits(T n) {
			if (n >= powers[9]) {
				if (n >= powers[13]) {
					if (n >= powers[16]) {
						if (n >= powers[17]) {
							if (n >= powers[18]) return 19;
							return 18;
						}
						return 17;
					}
					if (n >= powers[14]) {
						if (n >= powers[15]) return 16;
						return 15;
					}
					return 14;
				}
				if (n >= powers[11]) {
					if (n >= powers[12]) return 13;
					return 12;
				}
				if (n >= powers[10]) return 11;
				return 10;
			}
			if (n >= powers[4]) {
				if (n >= powers[7]) {
					if (n >= powers[8]) return 9;
					return 8;
				}
				if (n >= powers[5]) {
					if (n >= powers[6]) return 7;
					return 6;
				}
				return 5;
			}
			if (n >= powers[2]) {
				if (n >= powers[3]) return 4;
				return 3;
			}
			if (n >= powers[1]) return 2;
			return 1;
		}

	  public:
		Printer() = default;
		~Printer() { flush(); }
		void flush() {
			fwrite(outbuf, 1, pos, stdout);
			pos = 0;
		}
		void print() {}
		void print(char c) {
			outbuf[pos++] = c;
			if (__builtin_expect(pos == buf_size, 0)) flush();
		}
		void print(char* s) {
			while (*s != 0) {
				outbuf[pos++] = *s++;
				if (pos == buf_size) flush();
			}
		}
		void print(const std::string& x) {
			for (char c : x) {
				outbuf[pos++] = c;
				if (pos == buf_size) flush();
			}
		}
		template <typename T,
				  std::enable_if_t<std::is_integral<T>::value, std::nullptr_t> = nullptr>
		void print(T x) {
			if (__builtin_expect(pos + integer_size >= buf_size, 0)) flush();
			if (x < 0) print('-'), x = -x;
			size_t digit = integer_digits(x);
			size_t len = digit;
			while (len >= 4) {
				len -= 4;
				memcpy(outbuf + pos + len, block_str.get() + (x % block_size) * 4, 4);
				x /= 10000;
			}
			memcpy(outbuf + pos, block_str.get() + x * 4 + 4 - len, len);
			pos += digit;
		}
		template <typename T, class... Args>
		void print(const T& x, const Args&... args) {
			print(x);
			print(' ');
			print(args...);
		}
		template <class... Args>
		void println(const Args&... args) {
			print(args...);
			print('\n');
		}
		template <typename T,
				  std::enable_if_t<std::is_same_v<T, char> || std::is_same_v<T, char*> ||
									   std::is_same_v<T, std::string> || std::is_integral_v<T>,
								   std::nullptr_t> = nullptr>
		Printer& operator<<(const T& x) {
			print(x);
			return *this;
		}
	};
	const std::unique_ptr<char[]> Printer::block_str = Printer::precompute();
};	// namespace FastIO

/**
 * @title Fast IO library
 */
#line 3 "graph/Dinic.hpp"
class Dinic {
	class edge {
	  public:
		int to;
		lint cap;
		int rev, id;
	};
	int N, idx = 0;
	std::vector<std::vector<edge>> vec;
	std::vector<int> iter, level;
	bool bfs(int s, int t) {
		level.assign(N, -1);
		level[s] = 0;
		std::queue<int> que;
		que.push(s);
		while (!que.empty()) {
			int node = que.front();
			que.pop();
			if (level[node] == level[t]) break;
			for (const auto& i : vec[node]) {
				if (i.cap > 0 && level[i.to] == -1) {
					level[i.to] = level[node] + 1;
					que.push(i.to);
				}
			}
		}
		return level[t] != -1;
	}
	lint dfs(int node, int t, lint f) {
		if (node == t) return f;
		for (int& i = iter[node]; i < vec[node].size(); i++) {
			edge& e = vec[node][i];
			if (e.cap > 0 && level[node] < level[e.to] && level[e.to] <= level[t]) {
				lint d = dfs(e.to, t, std::min(f, e.cap));
				if (d > 0) {
					e.cap -= d;
					vec[e.to][e.rev].cap += d;
					return d;
				}
			}
		}
		return 0;
	}

  public:
	Dinic(int n) : N(n) {
		vec.resize(N);
		level.resize(N);
		iter.resize(N);
	}
	void reset() {
		rep(i, N) {
			for (auto& j : vec[i]) {
				if (j.id != -1) {
					vec[j.to][j.rev].cap += j.cap;
					j.cap = 0;
				}
			}
		}
	}
	void clear() { *this = Dinic(N); }
	void add_edge(int from, int to, lint cap) {
		vec[from].push_back({to, cap, (int)vec[to].size(), -1});
		vec[to].push_back({from, 0, (int)vec[from].size() - 1, idx++});
	}
	lint max_flow(int s, int t) {
		lint res = 0;
		std::chrono::system_clock::time_point start, end;
		int sum = 0;
		while (true) {
			// start = std::chrono::system_clock::now();
			bfs(s, t);
			if (level[t] < 0) {
				// std::cout << sum << '\n';
				return res;
			}
			iter.assign(N, 0);
			lint f;
			while ((f = dfs(s, t, LINF)) > 0) res += f;
			// end = std::chrono::system_clock::now();
			// sum += std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count();
		}
	}
	std::vector<lint> restore() const {
		std::vector<lint> res(idx);
		rep(i, N) {
			for (const auto& j : vec[i]) {
				if (j.id != -1) res[j.id] = j.cap;
			}
		}
		return res;
	}
};

/**
 * @title Dinic's algorithm
 */
#line 5 "test/yosupo/bipartitematching.test.cpp"
FastIO::Scanner cin;
FastIO::Printer cout;
int L, R, M, a[200010], b[200010];
int main() {
	cin >> L >> R >> M;
	Dinic flow(L + R + 2);
	REP(i, L) flow.add_edge(0, i, 1);
	for (int i = L + 1; i <= L + R; i++) flow.add_edge(i, L + R + 1, 1);
	rep(i, M) {
		cin >> a[i] >> b[i];
		flow.add_edge(a[i] + 1, b[i] + L + 1, 1);
	}
	cout << flow.max_flow(0, L + R + 1) << '\n';
	auto vec = flow.restore();
	rep(i, M) {
		if (vec[i + L + R]) cout << a[i] << ' ' << b[i] << '\n';
	}
	return 0;
}

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