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#include <iostream>
#include <cmath>
#include <functional>
#include <random>
#include <vector>
#include <limits>
#include "randutils/randutils.hpp"
#include "pcg-cpp/include/pcg_random.hpp"
using Rng = randutils::random_generator<pcg32>;
class HalfEdge;
class Vertex {
private:
unsigned index;
public:
std::vector<HalfEdge*> neighbors;
void setIndex(unsigned i) {index = i;}
unsigned getIndex() const {return index;}
void addEdge(HalfEdge& e) {
neighbors.push_back(&e);
}
};
class HalfEdge {
private:
Vertex* tail;
Vertex* head;
public:
double oldX;
double X;
double weight;
void setVertices(Vertex& vt, Vertex& vh) {
tail = &vt;
head = &vh;
}
Vertex& getHead() {
return *head;
}
Vertex& getTail() {
return *tail;
}
const Vertex& getHead() const {
return *head;
}
const Vertex& getTail() const {
return *tail;
}
};
class BipartiteGraph {
public:
std::vector<Vertex> redVertices;
std::vector<Vertex> blueVertices;
std::vector<HalfEdge> redEdges;
std::vector<HalfEdge> blueEdges;
BipartiteGraph(unsigned n, Rng& r) : redVertices(n * (n + 1)), blueVertices(n * (n + 1)), redEdges(pow(2 * n, 2)), blueEdges(pow(2 * n, 2)) {
for (unsigned i = 0; i < redVertices.size(); i++) {
redVertices[i].setIndex(i);
blueVertices[i].setIndex(i);
}
for (unsigned i = 0; i < redEdges.size(); i++) {
Vertex& blueVertex = blueVertices[(i % (2 * n)) / 2 + n * (((i + 2*n) / 4) / n)];
Vertex& redVertex = redVertices[(1+(i % (2 * n))) / 2 + (n + 1) * ((i / 4) / (n))];
redEdges[i].setVertices(redVertex, blueVertex);
blueEdges[i].setVertices(blueVertex, redVertex);
redVertex.addEdge(redEdges[i]);
blueVertex.addEdge(blueEdges[i]);
redEdges[i].X = 0;
blueEdges[i].X = 0;
redEdges[i].oldX = 0;
blueEdges[i].oldX = 0;
double w = r.variate<double, std::exponential_distribution>(1);
redEdges[i].weight = w;
blueEdges[i].weight = w;
}
}
void propagateBeliefs() {
for (HalfEdge& e : redEdges) {
double Xt = std::numeric_limits<double>::infinity();
for (const HalfEdge* en : e.getHead().neighbors) {
if (e.getTail().getIndex() != en->getHead().getIndex()) {
Xt = std::min(en->weight - en->oldX, Xt);
}
}
e.X = Xt;
}
for (HalfEdge& e : blueEdges) {
double Xt = std::numeric_limits<double>::infinity();
for (const HalfEdge* en : e.getHead().neighbors) {
if (e.getTail().getIndex() != en->getHead().getIndex()) {
Xt = std::min(en->weight - en->oldX, Xt);
}
}
e.X = Xt;
}
for (HalfEdge& e : redEdges) {
e.oldX = e.X;
}
for (HalfEdge& e : blueEdges) {
e.oldX = e.X;
}
}
};
int main() {
Rng r;
BipartiteGraph G(10, r);
for (unsigned i = 0; i < 1000; i++) {
G.propagateBeliefs();
// std::cout << G.redEdges[40].X << " " << G.blueEdges[40].X << std::endl;
}
for (unsigned i = 0; i < G.blueEdges.size(); i++) {
std::cout << G.blueEdges[i].getTail().getIndex() << " " << G.blueEdges[i].getHead().getIndex() + G.blueVertices.size() << std::endl;
}
for (unsigned i = 0; i < G.blueEdges.size(); i++) {
if (G.blueEdges[i].X + G.redEdges[i].X >= 0) {
std::cout << G.blueEdges[i].getTail().getIndex() << " " << G.blueEdges[i].getHead().getIndex() + G.blueVertices.size() << std::endl;
}
}
}
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