Program Listing for File local_search_intra.cpp

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#include "cvrp/local_search_intra.hpp"

#include <iostream>
#include <numeric>

constexpr double margin_of_error = 0.00001;

LocalSearchIntraSolution::LocalSearchIntraSolution(
    const std::vector<Node>& nodes, const std::vector<Vehicle>& vehicles,
    const std::vector<std::vector<double>>& distanceMatrix)
    : Solution(nodes, vehicles, distanceMatrix) {
  CreateInitialSolution();
}

LocalSearchIntraSolution::LocalSearchIntraSolution(const Problem& p)
    : Solution(p.nodes_, p.vehicles_, p.distanceMatrix_) {
  CreateInitialSolution();
}

LocalSearchIntraSolution::LocalSearchIntraSolution(const Solution& s)
    : Solution(s) {
  if (!s.CheckSolutionValid()) {
    std::cout << "The input solution is invalid. Exiting." << '\n';
    exit(0);
  }
}

void LocalSearchIntraSolution::Solve() {
  for (auto& v : vehicles_) {
    while (true) {
      double delta = 0;
      int best_c = -1;
      int best_r = -1;
      for (size_t cur = 1; cur < v.nodes_.size() - 1; cur++) {
        const int v_cur = v.nodes_[cur];
        const int v_prev = v.nodes_[cur - 1];
        const int v_next_c = v.nodes_[cur + 1];
        const double cost_reduction = distanceMatrix_[v_prev][v_next_c] -
                                      distanceMatrix_[v_prev][v_cur] -
                                      distanceMatrix_[v_cur][v_next_c];
        for (size_t rep = 1; rep < v.nodes_.size() - 1; rep++) {
          if (rep != cur && rep != cur - 1) {
            const int v_rep = v.nodes_[rep];
            const int v_next_r = v.nodes_[rep + 1];
            const double cost_increase = distanceMatrix_[v_rep][v_cur] +
                                         distanceMatrix_[v_cur][v_next_r] -
                                         distanceMatrix_[v_rep][v_next_r];
            if (cost_increase + cost_reduction < delta) {
              delta = cost_increase + cost_reduction;
              best_c = cur;
              best_r = rep;
            }
          }
        }
      }

      if (delta > -margin_of_error) {
        break;
      }
      const int val_best_c = *std::next(v.nodes_.begin(), best_c);
      v.nodes_.erase(std::next(v.nodes_.begin(), best_c));
      if (best_c < best_r) {
        v.nodes_.insert(std::next(v.nodes_.begin(), best_r), val_best_c);
      } else {
        v.nodes_.insert(std::next(v.nodes_.begin(), best_r + 1), val_best_c);
      }
      v.CalculateCost(distanceMatrix_);
    }
  }
  double cost = std::accumulate(
      std::begin(vehicles_), std::end(vehicles_), 0.0,
      [](const double sum, const Vehicle& v) { return sum + v.cost_; });
  std::cout << "Cost: " << cost << '\n';
  for (const auto& i : nodes_) {
    if (!i.is_routed_) {
      std::cout << "Unreached node: " << '\n';
      std::cout << i << '\n';
    }
  }
  std::cout << "Solution valid: " << CheckSolutionValid() << '\n';
}