binarybaddies/PathFinder.cpp at main · a-porche/binarybaddies · GitHub

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#include "PathFinder.h"
#include <queue>
#include <map>
#include <set>
#include <algorithm>
#include <iostream>
#include <limits>
#include <cmath>

PathFinder::PathFinder(std::shared_ptr<RailNetwork> net) : network(net) {}

double PathFinder::calculateHeuristic(int station1_id, int station2_id) const {
    auto s1 = network->getStation(station1_id);
    auto s2 = network->getStation(station2_id);
    if (!s1 || !s2) return 0.0;
    return s1->location.distanceTo(s2->location);
}

std::vector<int> PathFinder::reconstructPath(const std::map<int, int>& came_from, int start, int goal) const {
    std::vector<int> path;
    int current = goal;
    while (current != start) {
        path.push_back(current);
        auto it = came_from.find(current);
        if (it == came_from.end()) {
            return {};
        }
        current = it->second;
    }
    path.push_back(start);
    std::reverse(path.begin(), path.end());
    return path;
}

std::vector<int> PathFinder::findOptimalPath(int start_station_id, int goal_station_id) {
    if (start_station_id == goal_station_id) {
        return {start_station_id};
    }

    auto comp = [](const PathNode& a, const PathNode& b) {
        return a.f_cost() > b.f_cost();
    };
    std::priority_queue<PathNode, std::vector<PathNode>, decltype(comp)> open_set(comp);

    std::map<int, double> g_scores;
    std::map<int, int> came_from;
    std::set<int> closed_set;

    double h_start = calculateHeuristic(start_station_id, goal_station_id);
    open_set.push(PathNode(start_station_id, 0.0, h_start));
    g_scores[start_station_id] = 0.0;

    while (!open_set.empty()) {
        PathNode current = open_set.top();
        open_set.pop();

        if (current.station_id == goal_station_id) {
            return reconstructPath(came_from, start_station_id, goal_station_id);
        }

        if (closed_set.find(current.station_id) != closed_set.end()) {
            continue;
        }
        closed_set.insert(current.station_id);

        const auto& neighbors = network->getAdjacentStations(current.station_id);
        for (int neighbor_id : neighbors) {
            if (closed_set.find(neighbor_id) != closed_set.end()) {
                continue;
            }

            auto track = network->getTrackBetween(current.station_id, neighbor_id);
            if (!track || !track->is_active) {
                continue;
            }

            double tentative_g = current.g_cost + track->distance;

            if (g_scores.find(neighbor_id) == g_scores.end() || tentative_g < g_scores[neighbor_id]) {
                g_scores[neighbor_id] = tentative_g;
                came_from[neighbor_id] = current.station_id;

                double h = calculateHeuristic(neighbor_id, goal_station_id);
                open_set.push(PathNode(neighbor_id, tentative_g, h));
            }
        }
    }

    return {};
}

double PathFinder::calculatePathDistance(const std::vector<int>& path) const {
    if (path.size() < 2) return 0.0;

    double total_distance = 0.0;
    for (size_t i = 0; i < path.size() - 1; ++i) {
        auto track = network->getTrackBetween(path[i], path[i + 1]);
        if (track) {
            total_distance += track->distance;
        }
    }
    return total_distance;
}

double PathFinder::estimateTravelTime(const std::vector<int>& path) const {
    if (path.size() < 2) return 0.0;

    double total_time = 0.0;
    for (size_t i = 0; i < path.size() - 1; ++i) {
        auto track = network->getTrackBetween(path[i], path[i + 1]);
        if (track) {
            total_time += (track->distance / track->speed_limit);
        }
    }
    return total_time;
}

void PathFinder::printPath(const std::vector<int>& path) const {
    if (path.empty()) {
        std::cout << "No path found" << std::endl;
        return;
    }

    std::cout << "Path: ";
    for (size_t i = 0; i < path.size(); ++i) {
        auto station = network->getStation(path[i]);
        if (station) {
            std::cout << station->name;
            if (i < path.size() - 1) {
                std::cout << " -> ";
            }
        }
    }
    std::cout << std::endl;
    std::cout << "Distance: " << calculatePathDistance(path) << " km" << std::endl;
    std::cout << "Est. Time: " << estimateTravelTime(path) << " hours" << std::endl;
}