cplib-cpp
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flow/maxflow.hpp
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- Last update: 2022-12-07 23:52:43+09:00
- Include:
#include "flow/maxflow.hpp" - Link: https://atcoder.github.io/ac-library/production/document_ja/maxflow.html>
Required by
Verified with
- flow/test/b_flow.test.cpp
- flow/test/maxflow.test.cpp
- flow/test/mcf_costscaling.bflow.test.cpp
- flow/test/mcf_costscaling.test.cpp
Code
#pragma once
#include <algorithm>
#include <cassert>
#include <fstream>
#include <limits>
#include <string>
#include <vector>
// CUT begin
// MaxFlow based and AtCoder Library, single class, no namespace, no private variables, compatible
// with C++11 Reference: <https://atcoder.github.io/ac-library/production/document_ja/maxflow.html>
template <class Cap> struct mf_graph {
struct simple_queue_int {
std::vector<int> payload;
int pos = 0;
void reserve(int n) { payload.reserve(n); }
int size() const { return int(payload.size()) - pos; }
bool empty() const { return pos == int(payload.size()); }
void push(const int &t) { payload.push_back(t); }
int &front() { return payload[pos]; }
void clear() {
payload.clear();
pos = 0;
}
void pop() { pos++; }
};
mf_graph() : _n(0) {}
mf_graph(int n) : _n(n), g(n) {}
int add_edge(int from, int to, Cap cap) {
assert(0 <= from && from < _n);
assert(0 <= to && to < _n);
assert(0 <= cap);
int m = int(pos.size());
pos.push_back({from, int(g[from].size())});
int from_id = int(g[from].size());
int to_id = int(g[to].size());
if (from == to) to_id++;
g[from].push_back(_edge{to, to_id, cap});
g[to].push_back(_edge{from, from_id, 0});
return m;
}
struct edge {
int from, to;
Cap cap, flow;
};
edge get_edge(int i) {
int m = int(pos.size());
assert(0 <= i && i < m);
auto _e = g[pos[i].first][pos[i].second];
auto _re = g[_e.to][_e.rev];
return edge{pos[i].first, _e.to, _e.cap + _re.cap, _re.cap};
}
std::vector<edge> edges() {
int m = int(pos.size());
std::vector<edge> result;
for (int i = 0; i < m; i++) { result.push_back(get_edge(i)); }
return result;
}
void change_edge(int i, Cap new_cap, Cap new_flow) {
int m = int(pos.size());
assert(0 <= i && i < m);
assert(0 <= new_flow && new_flow <= new_cap);
auto &_e = g[pos[i].first][pos[i].second];
auto &_re = g[_e.to][_e.rev];
_e.cap = new_cap - new_flow;
_re.cap = new_flow;
}
std::vector<int> level, iter;
simple_queue_int que;
void _bfs(int s, int t) {
std::fill(level.begin(), level.end(), -1);
level[s] = 0;
que.clear();
que.push(s);
while (!que.empty()) {
int v = que.front();
que.pop();
for (auto e : g[v]) {
if (e.cap == 0 || level[e.to] >= 0) continue;
level[e.to] = level[v] + 1;
if (e.to == t) return;
que.push(e.to);
}
}
}
Cap _dfs(int v, int s, Cap up) {
if (v == s) return up;
Cap res = 0;
int level_v = level[v];
for (int &i = iter[v]; i < int(g[v].size()); i++) {
_edge &e = g[v][i];
if (level_v <= level[e.to] || g[e.to][e.rev].cap == 0) continue;
Cap d = _dfs(e.to, s, std::min(up - res, g[e.to][e.rev].cap));
if (d <= 0) continue;
g[v][i].cap += d;
g[e.to][e.rev].cap -= d;
res += d;
if (res == up) return res;
}
level[v] = _n;
return res;
}
Cap flow(int s, int t) { return flow(s, t, std::numeric_limits<Cap>::max()); }
Cap flow(int s, int t, Cap flow_limit) {
assert(0 <= s && s < _n);
assert(0 <= t && t < _n);
assert(s != t);
level.assign(_n, 0), iter.assign(_n, 0);
que.clear();
Cap flow = 0;
while (flow < flow_limit) {
_bfs(s, t);
if (level[t] == -1) break;
std::fill(iter.begin(), iter.end(), 0);
Cap f = _dfs(t, s, flow_limit - flow);
if (!f) break;
flow += f;
}
return flow;
}
std::vector<bool> min_cut(int s) {
std::vector<bool> visited(_n);
simple_queue_int que;
que.push(s);
while (!que.empty()) {
int p = que.front();
que.pop();
visited[p] = true;
for (auto e : g[p]) {
if (e.cap && !visited[e.to]) {
visited[e.to] = true;
que.push(e.to);
}
}
}
return visited;
}
void dump_graphviz(std::string filename = "maxflow") const {
std::ofstream ss(filename + ".DOT");
ss << "digraph{\n";
for (int i = 0; i < _n; i++) {
for (const auto &e : g[i]) {
if (e.cap > 0) ss << i << "->" << e.to << "[label=" << e.cap << "];\n";
}
}
ss << "}\n";
ss.close();
return;
}
int _n;
struct _edge {
int to, rev;
Cap cap;
};
std::vector<std::pair<int, int>> pos;
std::vector<std::vector<_edge>> g;
};#line 2 "flow/maxflow.hpp"
#include <algorithm>
#include <cassert>
#include <fstream>
#include <limits>
#include <string>
#include <vector>
// CUT begin
// MaxFlow based and AtCoder Library, single class, no namespace, no private variables, compatible
// with C++11 Reference: <https://atcoder.github.io/ac-library/production/document_ja/maxflow.html>
template <class Cap> struct mf_graph {
struct simple_queue_int {
std::vector<int> payload;
int pos = 0;
void reserve(int n) { payload.reserve(n); }
int size() const { return int(payload.size()) - pos; }
bool empty() const { return pos == int(payload.size()); }
void push(const int &t) { payload.push_back(t); }
int &front() { return payload[pos]; }
void clear() {
payload.clear();
pos = 0;
}
void pop() { pos++; }
};
mf_graph() : _n(0) {}
mf_graph(int n) : _n(n), g(n) {}
int add_edge(int from, int to, Cap cap) {
assert(0 <= from && from < _n);
assert(0 <= to && to < _n);
assert(0 <= cap);
int m = int(pos.size());
pos.push_back({from, int(g[from].size())});
int from_id = int(g[from].size());
int to_id = int(g[to].size());
if (from == to) to_id++;
g[from].push_back(_edge{to, to_id, cap});
g[to].push_back(_edge{from, from_id, 0});
return m;
}
struct edge {
int from, to;
Cap cap, flow;
};
edge get_edge(int i) {
int m = int(pos.size());
assert(0 <= i && i < m);
auto _e = g[pos[i].first][pos[i].second];
auto _re = g[_e.to][_e.rev];
return edge{pos[i].first, _e.to, _e.cap + _re.cap, _re.cap};
}
std::vector<edge> edges() {
int m = int(pos.size());
std::vector<edge> result;
for (int i = 0; i < m; i++) { result.push_back(get_edge(i)); }
return result;
}
void change_edge(int i, Cap new_cap, Cap new_flow) {
int m = int(pos.size());
assert(0 <= i && i < m);
assert(0 <= new_flow && new_flow <= new_cap);
auto &_e = g[pos[i].first][pos[i].second];
auto &_re = g[_e.to][_e.rev];
_e.cap = new_cap - new_flow;
_re.cap = new_flow;
}
std::vector<int> level, iter;
simple_queue_int que;
void _bfs(int s, int t) {
std::fill(level.begin(), level.end(), -1);
level[s] = 0;
que.clear();
que.push(s);
while (!que.empty()) {
int v = que.front();
que.pop();
for (auto e : g[v]) {
if (e.cap == 0 || level[e.to] >= 0) continue;
level[e.to] = level[v] + 1;
if (e.to == t) return;
que.push(e.to);
}
}
}
Cap _dfs(int v, int s, Cap up) {
if (v == s) return up;
Cap res = 0;
int level_v = level[v];
for (int &i = iter[v]; i < int(g[v].size()); i++) {
_edge &e = g[v][i];
if (level_v <= level[e.to] || g[e.to][e.rev].cap == 0) continue;
Cap d = _dfs(e.to, s, std::min(up - res, g[e.to][e.rev].cap));
if (d <= 0) continue;
g[v][i].cap += d;
g[e.to][e.rev].cap -= d;
res += d;
if (res == up) return res;
}
level[v] = _n;
return res;
}
Cap flow(int s, int t) { return flow(s, t, std::numeric_limits<Cap>::max()); }
Cap flow(int s, int t, Cap flow_limit) {
assert(0 <= s && s < _n);
assert(0 <= t && t < _n);
assert(s != t);
level.assign(_n, 0), iter.assign(_n, 0);
que.clear();
Cap flow = 0;
while (flow < flow_limit) {
_bfs(s, t);
if (level[t] == -1) break;
std::fill(iter.begin(), iter.end(), 0);
Cap f = _dfs(t, s, flow_limit - flow);
if (!f) break;
flow += f;
}
return flow;
}
std::vector<bool> min_cut(int s) {
std::vector<bool> visited(_n);
simple_queue_int que;
que.push(s);
while (!que.empty()) {
int p = que.front();
que.pop();
visited[p] = true;
for (auto e : g[p]) {
if (e.cap && !visited[e.to]) {
visited[e.to] = true;
que.push(e.to);
}
}
}
return visited;
}
void dump_graphviz(std::string filename = "maxflow") const {
std::ofstream ss(filename + ".DOT");
ss << "digraph{\n";
for (int i = 0; i < _n; i++) {
for (const auto &e : g[i]) {
if (e.cap > 0) ss << i << "->" << e.to << "[label=" << e.cap << "];\n";
}
}
ss << "}\n";
ss.close();
return;
}
int _n;
struct _edge {
int to, rev;
Cap cap;
};
std::vector<std::pair<int, int>> pos;
std::vector<std::vector<_edge>> g;
};