428 lines
12 KiB
C++
428 lines
12 KiB
C++
// vim: set ts=2 sw=2 et tw=80:
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// compile with
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// g++ -lpthread --std=c++11 -o c_prob/aco aco.cc
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include <pthread.h>
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#include <vector>
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#include <set>
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#include <iostream>
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#include <algorithm>
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#include <unistd.h>
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using namespace std;
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typedef unsigned int uint;
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ostream& operator<< (ostream& out, vector<uint> a) {
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out << "[";
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for (int i = 0; i < a.size() - 1; i++) {
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out << a[i] << ",";
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}
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out << a[a.size() - 1] << "]";
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return out;
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}
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const uint MAX_NODES = 1577;
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// alpha >= 0
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double alpha;
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// beta >= 1
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double beta;
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double pheromone_evaporation_coeff;
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double pheromone_constant;
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uint n_iterations;
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uint n_ants;
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uint n_nodes;
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double dist_matrix[MAX_NODES][MAX_NODES];
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double pheromone_map[MAX_NODES][MAX_NODES];
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double ant_updated_pheromone_map[MAX_NODES][MAX_NODES];
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double sh_dist;
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vector<uint> sh_route;
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bool first_pass;
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uint start;
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uint select_random(const set<uint> &s) {
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auto n = rand() % s.size(); // not _really_ random
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auto it = begin(s);
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advance(it, n); // 'advance' the iterator n times
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return *it;
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}
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struct ant {
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uint other;
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uint idx;
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pthread_t t_handle;
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uint location;
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double distance_travelled;
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set<uint> possible_locations;
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vector<uint> route;
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bool tour_complete = false;
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void init() {
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this->other = 0;
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this->distance_travelled = 0.0;
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this->route.clear();
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this->possible_locations.clear();
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for (size_t i = 0; i < n_nodes; i++) {
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this->possible_locations.insert(i);
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}
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this->location = start;
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this->update_route(start);
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this->tour_complete = false;
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};
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void update_route(uint new_loc) {
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this->route.push_back(new_loc);
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this->possible_locations.erase(new_loc);
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};
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uint pick_path() {
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if (first_pass) {
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return select_random(this->possible_locations);
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} else {
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double attractiveness[n_nodes];
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double sum_total = 0.0;
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vector<uint> idxs;
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for (uint loc : this->possible_locations) {
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idxs.push_back(loc);
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double pheromone_amount = pheromone_map[this->location][loc];
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double distance = dist_matrix[this->location][loc];
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if (distance == 0) { distance = 0.000000001; };
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attractiveness[loc] = pow(pheromone_amount, alpha) *
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pow(1 / distance, beta);
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//cerr << "ant " << idx << " attr[loc]=" << attractiveness[loc] << endl;
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sum_total += attractiveness[loc];
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if (isnan(sum_total)) { cerr << "nanalert " << attractiveness[loc] <<
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" " << pheromone_amount << " " << distance << endl; }
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}
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// it is possible to have small values for pheromone amount / distance,
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// such that with rounding errors this is equal to zero
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if (sum_total == 0.0) {
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// increment all zero's, such that they are the smallest non-zero
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// values supported by the system
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// source: http://stackoverflow.com/a/10426033/5343977
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for (uint loc : idxs) {
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attractiveness[loc] = nextafter(attractiveness[loc],
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std::numeric_limits<double>::infinity());
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}
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sum_total = nextafter(sum_total, std::numeric_limits<double>::infinity());
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}
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double toss = (double) rand() / (double) RAND_MAX;
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// cerr << "ant " << idx << " sum_total is " << sum_total << " toss is " << toss << endl;
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double cumulative = 0.0;
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for (uint loc : idxs) {
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double weight = (attractiveness[loc] / sum_total);
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//cerr << "ant " << idx << " w: " << weight + cumulative << endl;
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if (toss <= (weight + cumulative)) {
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return loc;
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}
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cumulative += weight;
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}
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cerr << "cum " << cumulative << " n " << idxs.size() << " toss " << toss << endl;
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sleep(1);
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other++;
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// cerr << "ant " << idx << " change statement" << endl;
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return idxs[idxs.size() - 1];
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}
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};
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void traverse(uint next) {
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this->update_route(next);
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this->distance_travelled += dist_matrix[this->location][next];
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this->location = next;
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//cerr << "traversing " << next << " dist: " << this->distance_travelled << endl;
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}
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void run() {
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// cerr << "started ant - # can pick: " << this->possible_locations.size() << endl;
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while (!this->possible_locations.empty()) {
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uint next = this->pick_path();
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this->traverse(next);
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}
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this->distance_travelled += dist_matrix[this->route[this->route.size() - 1]]
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[this->route[0]];
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// cerr << "stopped ant" << endl;
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this->tour_complete = true;
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}
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};
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void *ant_thread (void *ant_ptr) {
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ant& ant = *((struct ant *) ant_ptr);
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ant.run();
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return NULL;
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}
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ant* ants;
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void init_ants() {
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for (size_t i = 0; i < n_ants; i++) {
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ants[i].init();
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ants[i].idx = i;
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}
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}
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pthread_mutex_t mut;
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void init_aco() {
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pthread_mutex_init(&mut, NULL);
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start = 0;
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first_pass = true;
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memset(pheromone_map, 0, sizeof(pheromone_map));
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memset(ant_updated_pheromone_map, 0, sizeof(ant_updated_pheromone_map));
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init_ants();
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sh_dist = -1.0;
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}
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void populate_ant_updated_pheromone_map(ant& ant) {
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for (size_t i = 0; i < ant.route.size(); i++) {
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size_t j = (i + 1) % n_nodes;
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double current_ph = ant_updated_pheromone_map[ant.route[i]][ant.route[j]];
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double new_ph = pheromone_constant / ant.distance_travelled;
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ant_updated_pheromone_map[ant.route[i]][ant.route[j]] =
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ant_updated_pheromone_map[ant.route[j]][ant.route[i]] =
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current_ph + new_ph;
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}
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}
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void update_pheromone_map() {
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for (size_t i = 0; i < n_nodes; i++) {
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for (size_t j = 0; j < n_nodes; j++) {
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pheromone_map[i][j] = (1 - pheromone_evaporation_coeff) *
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pheromone_map[i][j] + ant_updated_pheromone_map[i][j];
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}
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}
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}
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void mainloop() {
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for (size_t i = 0; i < n_iterations; i++) {
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srand(i);
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//cerr << "starting ants" << endl;
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for (uint j = 0; j < n_ants; j++) {
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pthread_create(&(ants[j].t_handle), NULL, ant_thread, &(ants[j]));
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}
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// cerr << "joining ants" << endl;
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for (uint j = 0; j < n_ants; j++) {
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pthread_join(ants[j].t_handle, NULL);
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}
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//cerr << "summing ants" << endl;
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uint os = 0;
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for (uint j = 0; j < n_ants; j++) {
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os += ants[j].other;
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populate_ant_updated_pheromone_map(ants[j]);
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if (sh_dist < 0 || ants[j].distance_travelled < sh_dist) {
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sh_dist = ants[j].distance_travelled;
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sh_route = ants[j].route;
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cerr << "new short distance is " << sh_dist << " ant " << j << endl;
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}
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}
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update_pheromone_map();
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first_pass = false;
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init_ants();
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memset(ant_updated_pheromone_map, 0, sizeof(ant_updated_pheromone_map));
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/*double real = 0;
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for (uint k = 0; k < n_nodes; k++) {
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real += dist_matrix[sh_route[k]][sh_route[(k + 1) % n_nodes]];
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}*/
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cerr << "iteration " << i << ": dist " << sh_dist << endl;// << " os " << os << " rdist " << real << endl;
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/*
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uint nnz = 0;
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double sum = 0, min = 1.0/0.0, max = -1.0/0.0;
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for (int i = 0; i < n_nodes; i++) {
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for (int j = 0; j < n_nodes - 1; j++) {
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if (pheromone_map[i][j] != 0.0) nnz++;
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sum += pheromone_map[i][j];
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if (min > pheromone_map[i][j]) min = pheromone_map[i][j];
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if (max < pheromone_map[i][j]) max = pheromone_map[i][j];
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}
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}
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cerr << "phmap: avg " << sum / (double) (n_nodes * n_nodes) << " min " << min << " max " << max << " nnz " << nnz << endl;*/
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}
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}
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uint two_opt() {
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uint swaps = 0;
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for (int i = 0; i < n_nodes - 1; i++) {
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for (int j = i+2; j < n_nodes; j++) {
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size_t ip = i == 0 ? (n_nodes - 1) : (i - 1);
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size_t ei = sh_route[i], ej = sh_route[j], eii = sh_route[ip],
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ejj = sh_route[j];
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double new_dist = sh_dist - dist_matrix[eii][ei] - dist_matrix[ejj][ej]
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+ dist_matrix[ei][ej] + dist_matrix[ejj][eii];
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if (new_dist < sh_dist) {
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//cerr << "2opt " << i << " " << j << ": " << new_dist << endl;
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sh_dist = new_dist;
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reverse(sh_route.begin() + i, sh_route.begin() + j);
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swaps++;
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}
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}
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}
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return swaps;
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}
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uint two_five_opt() {
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uint swaps = 0;
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for (int i = 0; i < n_nodes - 2; i++) {
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for (int j = i+2; j < n_nodes; j++) {
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size_t ip = i == 0 ? (n_nodes - 1) : (i - 1);
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size_t x1 = sh_route[ip];
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size_t x2 = sh_route[i];
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size_t x3 = sh_route[i+1];
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size_t y3 = sh_route[j-2];
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size_t y1 = sh_route[j-1];
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size_t y2 = sh_route[j];
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double var_a = sh_dist - dist_matrix[x2][x1] - dist_matrix[y2][y1]
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+ dist_matrix[x1][y1] + dist_matrix[y2][x2];
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double var_b = sh_dist - dist_matrix[x2][x1] - dist_matrix[y2][y1]
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- dist_matrix[x2][x3] + dist_matrix[x2][y2]
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+ dist_matrix[y1][x2] + dist_matrix[x1][x3];
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double var_c = sh_dist - dist_matrix[x2][x1] - dist_matrix[y2][y1]
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- dist_matrix[y1][y3] + dist_matrix[x1][y1]
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+ dist_matrix[y1][x2] + dist_matrix[y3][y2];
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if (var_a < sh_dist && var_a < var_b && var_a < var_c) {
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//cerr << "25opt(a) " << i << " " << j << ": " << var_a << endl;
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sh_dist = var_a;
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reverse(sh_route.begin() + i, sh_route.begin() + j);
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swaps++;
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} else if (var_b < sh_dist && var_b < var_a && var_b < var_c) {
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//cerr << "25opt(b) " << i << " " << j << ": " << var_b << endl;
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//cerr << vector<uint>(sh_route.begin() + i - 1, sh_route.begin() + j + 1) << endl;
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for (int k = i; k < j - 1; k++) {
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sh_route[k] = sh_route[k + 1];
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}
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sh_route[j - 1] = x2;
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//cerr << vector<uint>(sh_route.begin() + i - 1, sh_route.begin() + j + 1) << endl;
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sh_dist = var_b;
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swaps++;
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} else if (var_c < sh_dist && var_c < var_a && var_c < var_b) {
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//cerr << "25opt(c) " << i << " " << j << ": " << var_c << endl;
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//cerr << vector<uint>(sh_route.begin() + i - 1, sh_route.begin() + j + 1) << endl;
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for (int k = j - 2; k >= i; k--) {
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sh_route[k + 1] = sh_route[k];
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}
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sh_route[i] = y1;
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//cerr << vector<uint>(sh_route.begin() + i - 1, sh_route.begin() + j + 1) << endl;
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sh_dist = var_c;
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swaps++;
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}
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}
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}
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return swaps;
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}
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#define buffersize 100000
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int main(int argc, char** argv) {
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if (argc < 8) {
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cerr << argv[0] << " [n_nodes] [n_iter] [n_ants] [alpha] [beta] [evap] [weight]" << endl;
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return 1;
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}
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n_nodes = atoi(argv[1]);
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n_iterations = atoi(argv[2]);
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n_ants = atoi(argv[3]);
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sscanf(argv[4], "%lf", &alpha);
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sscanf(argv[5], "%lf", &beta);
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sscanf(argv[6], "%lf", &pheromone_evaporation_coeff);
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sscanf(argv[7], "%lf", &pheromone_constant);
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ant ants_arr[n_ants];
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ants = ants_arr;
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cerr << n_nodes << endl;
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char * pch;
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int row = 0, column = 0;
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char buffer[buffersize];
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for (size_t i = 0; i < n_nodes; i++) {
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fgets(buffer, buffersize, stdin);
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pch = strtok(buffer, " ");
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column = 0;
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while (pch != NULL) {
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sscanf(pch, "%lf", &(dist_matrix[row][column]));
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pch = strtok(NULL, " ");
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column++;
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}
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row++;
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}
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cerr << "reading done" << endl;
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/*uint nnz = 0;
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for (int i = 0; i < n_nodes; i++) {
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for (int j = 0; j < n_nodes - 1; j++) {
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if (dist_matrix[i][j] != 0.0) nnz++;
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}
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}
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cerr << "dist: nnz " << nnz << endl;*/
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init_aco();
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// scan and parse
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mainloop();
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//for (uint k = 0; k < n_nodes; k++) {
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// cerr << "p: " << sh_route[k] << ": " << dist_matrix[sh_route[k]][sh_route[(k + 1) % n_nodes]] << endl;
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//}
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cerr << "pre-optimization length: " << sh_dist << endl;
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uint i = 0;
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uint j = 0;
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do {
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//for (i = 0; i < 50; i++) {
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//cerr << "2opt round " << i << endl;
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//if(two_opt() == 0) break;
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//}
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for (j = 0; j < 50; j++) {
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//cerr << "25opt round " << j << endl;
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if(two_five_opt() == 0) break;
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}
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cerr << "optimizing length: " << sh_dist << endl;
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} while (i > 0 || j > 0);
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cerr << "optimized length: " << sh_dist << endl;
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cout << sh_route << endl;
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}
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