cplib-cpp
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flow/test/maxflow.pushrelabel.test.cpp
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- Last update: 2022-12-07 23:52:43+09:00
- Problem: http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_6_A
Depends on
Code
#include "../maxflow_pushrelabel.hpp"
#include <cassert>
#include <iostream>
#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_6_A"
using namespace std;
int main() {
cin.tie(nullptr), ios::sync_with_stdio(false);
int V, E;
cin >> V >> E;
mf_pushrelabel<int, 0, false> g00(V);
mf_pushrelabel<int, 0, true> g01(V);
mf_pushrelabel<int, 2, false> g10(V);
mf_pushrelabel<int, 2, true> g11(V);
while (E--) {
int u, v, c;
cin >> u >> v >> c;
g00.add_edge(u, v, c);
g01.add_edge(u, v, c);
g10.add_edge(u, v, c);
g11.add_edge(u, v, c);
}
auto f00 = g00.flow(0, V - 1);
auto f01 = g01.flow(0, V - 1);
auto f10 = g10.flow(0, V - 1);
auto f11 = g11.flow(0, V - 1);
assert(f00 == f01);
assert(f00 == f10);
assert(f00 == f11);
cout << f00 << '\n';
}#line 2 "flow/maxflow_pushrelabel.hpp"
#include <cassert>
#include <limits>
#include <utility>
#include <vector>
// Maxflow (push-relabel, highest-label)
// Complexity: O(N^2 M^(1/2))
template <class Cap, int GlobalRelabelFreq = 5, bool UseGapRelabeling = true>
struct mf_pushrelabel {
struct pque_ {
std::vector<std::pair<int, int>> even_, odd_;
int se, so;
void init(int n) { even_.resize(n), odd_.resize(n), se = so = 0; };
void clear() { se = so = 0; }
bool empty() const { return se + so == 0; }
void push(int i, int h) { (h & 1 ? odd_[so++] : even_[se++]) = {i, h}; }
int highest() const {
int a = se ? even_[se - 1].second : -1, b = so ? odd_[so - 1].second : -1;
return a > b ? a : b;
}
int pop() {
if (!se or (so and odd_[so - 1].second > even_[se - 1].second))
return odd_[--so].first;
return even_[--se].first;
}
} pque;
int _n;
struct _edge {
int to, rev;
Cap cap;
};
std::vector<std::vector<_edge>> g;
std::vector<std::pair<int, int>> pos;
mf_pushrelabel(int n) : _n(n), g(n) {
static_assert(GlobalRelabelFreq >= 0, "Global relabel parameter must be nonnegative.");
}
int add_edge(int from, int to, Cap cap) {
assert(0 <= from and from < _n);
assert(0 <= to and to < _n);
assert(0 <= cap);
int m = int(pos.size());
pos.emplace_back(from, int(g[from].size()));
int from_id = g[from].size(), to_id = g[to].size() + (from == to);
g[from].push_back({to, to_id, cap});
g[to].push_back({from, from_id, Cap(0)});
return m;
}
struct edge {
int from, to;
Cap cap, flow;
};
edge get_edge(int i) const {
int m = int(pos.size());
assert(0 <= i and i < m);
auto e = g[pos[i].first][pos[i].second], re = g[e.to][e.rev];
return edge{pos[i].first, e.to, e.cap + re.cap, re.cap};
}
std::vector<edge> edges() const {
std::vector<edge> ret(pos.size());
for (int i = 0; i < int(pos.size()); i++) ret[i] = get_edge(i);
return ret;
}
std::vector<int> dist;
std::vector<int> dcnt;
std::vector<Cap> excess;
int gap;
void global_relabeling(int t) {
dist.assign(_n, _n), dist[t] = 0;
static std::vector<int> q;
if (q.empty()) q.resize(_n);
q[0] = t;
int qb = 0, qe = 1;
pque.clear();
if (UseGapRelabeling) gap = 1, dcnt.assign(_n + 1, 0);
while (qb < qe) {
int now = q[qb++];
if (UseGapRelabeling) gap = dist[now] + 1, dcnt[dist[now]]++;
if (excess[now] > 0) pque.push(now, dist[now]);
for (const auto &e : g[now]) {
if (g[e.to][e.rev].cap and dist[e.to] == _n) {
dist[e.to] = dist[now] + 1;
while (int(q.size()) <= qe) q.push_back(0);
q[qe++] = e.to;
}
}
}
}
Cap flow(int s, int t) { return flow(s, t, std::numeric_limits<Cap>::max(), true); }
Cap flow(int s, int t, Cap flow_limit, bool retrieve = true) {
assert(0 <= s and s < _n);
assert(0 <= t and t < _n);
assert(s != t);
excess.resize(_n, 0);
excess[s] += flow_limit, excess[t] -= flow_limit;
dist.assign(_n, 0);
dist[s] = _n;
if (UseGapRelabeling) gap = 1, dcnt.assign(_n + 1, 0), dcnt[0] = _n - 1;
pque.init(_n);
for (auto &e : g[s]) _push(s, e);
_run(t);
Cap ret = excess[t] + flow_limit;
excess[s] += excess[t], excess[t] = 0;
if (retrieve) {
global_relabeling(s);
_run(s);
assert(excess == std::vector<Cap>(_n, 0));
}
return ret;
}
void _run(int t) {
if (GlobalRelabelFreq) global_relabeling(t);
int tick = pos.size() * GlobalRelabelFreq;
while (!pque.empty()) {
int i = pque.pop();
if (UseGapRelabeling and dist[i] > gap) continue;
int dnxt = _n * 2 - 1;
for (auto &e : g[i]) {
if (!e.cap) continue;
if (dist[e.to] == dist[i] - 1) {
_push(i, e);
if (excess[i] == 0) break;
} else {
if (dist[e.to] + 1 < dnxt) dnxt = dist[e.to] + 1;
}
}
if (excess[i] > 0) {
if (UseGapRelabeling) {
if (dnxt != dist[i] and dcnt[dist[i]] == 1 and dist[i] < gap) gap = dist[i];
if (dnxt == gap) gap++;
while (pque.highest() > gap) pque.pop();
if (dnxt > gap) dnxt = _n;
if (dist[i] != dnxt) dcnt[dist[i]]--, dcnt[dnxt]++;
}
dist[i] = dnxt;
if (!UseGapRelabeling or dist[i] < gap) pque.push(i, dist[i]);
}
if (GlobalRelabelFreq and --tick == 0) {
tick = pos.size() * GlobalRelabelFreq, global_relabeling(t);
}
}
return;
}
void _push(int i, _edge &e) {
Cap delta = e.cap < excess[i] ? e.cap : excess[i];
excess[i] -= delta, e.cap -= delta;
excess[e.to] += delta, g[e.to][e.rev].cap += delta;
if (excess[e.to] > 0 and excess[e.to] <= delta) {
if (!UseGapRelabeling or dist[e.to] <= gap) pque.push(e.to, dist[e.to]);
}
}
};
#line 3 "flow/test/maxflow.pushrelabel.test.cpp"
#include <iostream>
#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_6_A"
using namespace std;
int main() {
cin.tie(nullptr), ios::sync_with_stdio(false);
int V, E;
cin >> V >> E;
mf_pushrelabel<int, 0, false> g00(V);
mf_pushrelabel<int, 0, true> g01(V);
mf_pushrelabel<int, 2, false> g10(V);
mf_pushrelabel<int, 2, true> g11(V);
while (E--) {
int u, v, c;
cin >> u >> v >> c;
g00.add_edge(u, v, c);
g01.add_edge(u, v, c);
g10.add_edge(u, v, c);
g11.add_edge(u, v, c);
}
auto f00 = g00.flow(0, V - 1);
auto f01 = g01.flow(0, V - 1);
auto f10 = g10.flow(0, V - 1);
auto f11 = g11.flow(0, V - 1);
assert(f00 == f01);
assert(f00 == f10);
assert(f00 == f11);
cout << f00 << '\n';
}