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graph.cxx
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graph.cxx
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/**
* Dynamic Programming & Nearest Neighbour Algorithm for TSP
* File: graph.cxx
* Author: iJab(Zhan Caibao) zhancaibaoATgmail.com
* Date: 2013/02/20
*
*/
#include <iostream>
#include <stack>
#include <vector>
#include <list>
#include <set>
#include <string>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <limits>
#include "graph.hxx"
using namespace std;
// Helper function to print time
void print_current_time()
{
time_t rawtime;
struct tm * timeinfo;
time ( &rawtime );
timeinfo = localtime ( &rawtime );
printf ( "The current date/time is: %s", asctime (timeinfo) );
};
///////////////////////////////////////////////////////////////
/**
* Graph base class implementation
*
*/
graph::~graph()
{
}
/**
* Calculate shortest path for TSP with Dynamic Programmings
* @param int source : source vertex id
* @return int : number of path from source to other nodes
*/
double graph::dp_tsp(int source)
{
cout << "Dynamic Programming Calculating shortest path for TSP from vertex " << source << endl;
print_current_time();
cout << endl;
int _v_size = this->get_size();
if(source < 0 || source >= _v_size)
{
source = 0;
}
this->source = source;
// Do some clean
this->tsp_s_path.unvisited.clear();
this->tsp_s_path.type.clear();
vector<STATUS> pre_v;
vector<STATUS> cur_v;
// Init current vertex array
// Distance and shortest path from each vertex to source using empty vertices set. {Vi, {emtpy set}}
for(int i = 0; i < _v_size; i++)
{
if(i == source) continue; // Ignore source vertex
STATUS _v_status;
_v_status.cur_v = i;
_v_status.distance = this->get_cost(i, source);
cur_v.push_back(_v_status);
}
// Loop on each vertex
for(int j = 0; j < _v_size - 2; j++)
{
// Set previous vertex to current vertex array
pre_v = cur_v;
cur_v.clear();
for(int i = 0; i < _v_size; i++)
{
if(i == source) continue;
vector<STATUS>::iterator it;
for(it = pre_v.begin(); it != pre_v.end(); ++it)
{
STATUS temp = *it;
// Check if vertex i has been included in temp's path or not
int b_exist = false;
if(i == temp.cur_v)
b_exist = true;
else
{
vector<int>::iterator uv_it = temp.unvisited.begin();
for(; uv_it != temp.unvisited.end(); ++uv_it)
if(i == *uv_it)
{
b_exist = true;
break;
}
}
// If not exist
if(!b_exist)
{
STATUS _n_v_status = temp;
vector<int>::iterator int_iter = _n_v_status.unvisited.begin();
_n_v_status.unvisited.insert(int_iter, _n_v_status.cur_v);
_n_v_status.type.insert(_n_v_status.cur_v);
_n_v_status.distance += this->get_cost(i, _n_v_status.cur_v);
_n_v_status.cur_v = i;
cur_v.push_back(_n_v_status);
}
}
}
// Calculae the shortest path in current vertex's paths
this->tsp_paths.clear();
vector<STATUS>::iterator iter;
STATUS temp;
while(cur_v.size() > 0)
{
iter = cur_v.begin();
temp = *iter;
iter = cur_v.erase(iter);
for(; iter != cur_v.end(); )
{
bool need_inc = true;
if((temp.cur_v == (*iter).cur_v) && (temp.type == (*iter).type))
{
if((*iter).distance < temp.distance)
temp = *iter;
iter = cur_v.erase(iter);
need_inc = false;
}
if(need_inc) ++iter;
}
this->tsp_paths.push_back(temp);
}
// Check current minimum path array
cur_v = this->tsp_paths;
}
// Calculate the shortest path from source to every possible path
vector<STATUS>::iterator iter = this->tsp_paths.begin();
this->tsp_s_path = *iter;
this->m_dis = this->tsp_s_path.distance + this->get_cost(source, this->tsp_s_path.cur_v);
iter++;
for(; iter != this->tsp_paths.end(); iter++)
{
double temp_dis = this->get_cost(source, (*iter).cur_v) + (*iter).distance;
if(temp_dis < this->m_dis)
{
this->m_dis = temp_dis;
this->tsp_s_path = *iter;
}
}
cout << "Dynamic Calculating shortest path for TSP from vertex " << source << endl;
print_current_time();
cout << endl;
return this->m_dis;
}
/**
* Shortest path for TSP with Nearest Neighbour Heuristic algorithm
* @param source int
* @return int : all paths
*/
double graph::nn_tsp(int source)
{
if(this->is_empty_graph()) return 0;
cout << "Nearest Neighbour Algorithm Calculating shortest path for TSP ... " << endl;
print_current_time();
cout << endl;
int _v_size = this->get_size();
if(source < 0 || source >= _v_size)
source = 0;
this->source = source;
// Do some clean
this->tsp_s_path.unvisited.clear();
this->tsp_s_path.type.clear();
set<int> visited_v;
visited_v.insert(source);
// Loop to find the nearest vertex for current vertex till all vertices are marked visted
int current_v = source;
this->m_dis = 0;
while((int)visited_v.size() < _v_size)
{
pair<int, double> nearest_v = this->get_unvisited_nearest_neighbour(current_v, visited_v);
this->m_dis += nearest_v.second;
if(current_v == source)
{
this->tsp_s_path.cur_v = nearest_v.first;
this->tsp_s_path.distance = nearest_v.second;
}
else
{
this->tsp_s_path.unvisited.insert(this->tsp_s_path.unvisited.begin(), nearest_v.first);
this->tsp_s_path.distance += nearest_v.second;
}
// Set current vertex to the nearest neighbour and mark it as visited
current_v = nearest_v.first;
visited_v.insert(current_v);
// If it's the last one, add the distance between it and the source vertex
if(visited_v.size() == _v_size)
{
this->m_dis += this->get_cost(current_v, source);
}
}
cout << "Nearest Neighbour Algorithm Completed Calculating shortest path for TSP." << endl;
print_current_time();
cout << endl;
return this->m_dis;
}
/**
* Print the shortest path cost result
*/
void graph::print_result()
{
// Print Result
vector<int>::iterator iter_v;
cout << "Minimum distance is " << this->m_dis << endl;
cout << "The shortest path is " << this->source << "->" << this->tsp_s_path.cur_v;
for(iter_v = this->tsp_s_path.unvisited.begin(); iter_v != this->tsp_s_path.unvisited.end(); iter_v++)
cout<< "->"<< *iter_v;
cout << "->" << this->source << endl;
}
///////////////////////////////////////////////////////////////////////////////////
/**
* Implementation of 2-d array based graph
*
*/
/**
* Constructor of 2-d array based graph
* @param num int: size of vertices in the graph
* @return void
*/
twodarray_graph::twodarray_graph(int num) : graph(num)
{
if(num < 1)
{
this->adj_matrix = NULL;
}
else
{
// Init and new memory for graph
this->adj_matrix = new double*[num];
for(int i = 0; i < num; ++i)
{
this->adj_matrix[i] = new double[num];
// Set init value to INF_WEIGHT which means no path between vertices
for( int j = 0; j < num; ++j)
{
this->adj_matrix[i][j] = INF_WEIGHT;
}
}
}
}
/**
* Desstructor of 2-d array based graph
* @param num int: size of vertices in the graph
* @return void
*/
twodarray_graph::~twodarray_graph()
{
// Release resource
if(this->adj_matrix != NULL)
{
int _size = this->get_size();
for(int i = 0; i < _size; ++i)
{
delete []this->adj_matrix[i];
this->adj_matrix[i] = NULL;
}
delete []this->adj_matrix;
this->adj_matrix = NULL;
}
}
/**
* Add connected edge to graph
* @param int source : source vertex id
* @param int target : target vertex id
* @param double w : weight between these two vertices
* @return void
*/
void twodarray_graph::add_edge(int source, int target, double w)
{
// Not allocated memory for graph
if(this->adj_matrix == NULL)
return;
// Negative source or target
if(source < 0 || target < 0)
return;
// source or target is greater than number of vertices predefined
int _size = this->get_size();
if(source >= _size || target >= _size)
return;
if(source == target)
this->adj_matrix[source][target] = 0;
else
this->adj_matrix[source][target] = w < 1 ? INF_WEIGHT : w;
}
/**
* Remove connected edge between vertices from graph
* @param int source : source vertex id
* @param int target : target vertex id
* @return void
*/
void twodarray_graph::remove_edge(int source, int target)
{
// Make the weight between vertices to be -1 to disconnect
this->add_edge(source, target, INF_WEIGHT);
}
/**
* Get cost between two vertices
* @param int source : source vertex
* @param int target : target vertex
* @return double : cost between two vertices
*/
double twodarray_graph::get_cost(int source, int target)
{
int _v_size = this->get_size();
if(source < 0 || source >= _v_size
|| target < 0 || target >= _v_size)
return 0;
return this->adj_matrix[source][target];
}
/**
* Get nearest neighbour to the vertex
* @param int source : source vertex
* @param set<int> : visited vertices
* @return pair<int, double> : nearest vertex and the distance
*/
pair<int, double> twodarray_graph::get_unvisited_nearest_neighbour(int source, set<int> visited_v)
{
int _v_size = this->get_size();
double min_dist = INF_WEIGHT;
int nearest_v = source;
for(int i = 0; i < _v_size; ++i)
{
if(i == source || visited_v.find(i) != visited_v.end())
continue;
double alt_dist = this->get_cost(source, i);
if(min_dist > alt_dist)
{
min_dist = alt_dist;
nearest_v = i;
}
}
return pair<int, double>(nearest_v, min_dist);
}
/**
* Print graph
* @param void
* @return void
*/
void twodarray_graph::print_graph()
{
int _v_size = this->get_size();
for(int i = 0; i < _v_size; ++i)
{
for(int j = 0; j < _v_size; ++j)
{
cout << this->adj_matrix[i][j] << "\t\t";
}
cout << endl;
}
}