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MSTOpt.cpp
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MSTOpt.cpp
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/*
* MSTOpt.cpp
* ApproxMap
*
* Created by yonghui on 12/21/07.
* Copyright 2007 __MyCompanyName__. All rights reserved.
*
*/
#include "MSTOpt.h"
#include <iostream>
#include <queue>
#include <cassert>
#include "constants.h"
MSTOpt::MSTOpt(const vector<vector<double> > & _pair_wise_distances, int _num_bins, int nested_level)
: pair_wise_distances(_pair_wise_distances), number_of_bins(_num_bins) {
verbose_ = kMSTVerbose;
assert(pair_wise_distances.size() == number_of_bins);
nested_level_ = nested_level;
find_opt_order();
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
double MSTOpt::calculate_MST()
{
MST.resize(number_of_bins);
vector<double> estimated_distance(number_of_bins, numeric_limits<double>::max());
vector<bool> visitted(number_of_bins, false);
estimated_distance[0] = 0;
MST[0] = 0;
MST_lower_bound = 0 ;
for (int ii = 0 ; ii < number_of_bins ; ii++)
{
/*get the closest vertex*/
int closest_vertex = -1;
double shortest_distance = numeric_limits<double>::max();
/*
// print out something for debugging
for (int kk = 0; kk < number_of_bins; kk++){
cout << visitted[kk] << ' ';
}
cout << endl;
cout << "number of bins:" << number_of_bins << endl;
for (int kk = 0; kk < number_of_bins; kk++){
cout << estimated_distance[kk] << endl;
}
cout << endl;
*/
for (int jj = 0; jj < number_of_bins; jj ++)
{
if ((visitted[jj] == false) and (shortest_distance > estimated_distance[jj]))
{
closest_vertex = jj;
shortest_distance = estimated_distance[jj];
}
}
assert(closest_vertex != -1);
visitted[closest_vertex] = true;
MST_lower_bound = MST_lower_bound + shortest_distance;
/*update the estimated_distance vector*/
for (int jj = 0 ; jj < number_of_bins; jj++)
{
if ((visitted[jj] == false) and (estimated_distance[jj] > pair_wise_distances[closest_vertex][jj]))
{
estimated_distance[jj] = pair_wise_distances[closest_vertex][jj];
MST[jj] = closest_vertex;
}
}
}//end for
return MST_lower_bound;
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
void MSTOpt::find_opt_order()
{
calculate_MST();
if (verbose_) {
cout << "finished calculating MST" << endl;
}
new_serialization();
local_improvement();
// modified by yonghui on Feb 1st, 2008
// In order to avoid excessive long running time,
// block optimization is only applied to level 1 and level 2
if (nested_level_ <= 2) {
bool changed = true;
while (changed) {
changed = block_optimize();
}
}
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
void MSTOpt::local_improvement()
{
/*Run the heuristic only if the current_lowerbound is not equal to the current upperbound*/
if (current_upper_bound > MST_lower_bound)
{
bool changed = true;
/*a vector used to hold temporary elements*/
vector<int> tmp_storage(number_of_bins, -1);
while(changed)
{
/*execute the heuristic iteratively until no improvement can be made*/
while (changed)
{
changed = false;
/*Emulate the KL heuristic, consider all the possible 2-ops*/
/*ii is the id of the first edge to be removed, and jj is the id of the second edge to be removed*/
for (int ii = 1; ii < number_of_bins; ii ++)
{
for (int jj = ii+1; jj < number_of_bins; jj++)
{
/*step 1: determine if the new path/paths is shorter than the original path*/
double gone_edges_weight = pair_wise_distances[current_order[ii-1]][current_order[ii]] +
pair_wise_distances[current_order[jj-1]][current_order[jj]];
/* Block order2
order 1: 1 2 3
order 2: 2 1 3
order 3: 1 3 2
*/
int block_order_type = 0 ; // the default block order type
double lightest_edges_weight = gone_edges_weight;
bool flip_1 = false; //check if the orientation of the first block is flipped or not
bool flip_2 = false; //check if the orientation of the second block is flipped or not
bool flip_3 = false; //check if the orientation of the third block is flipped or not
/* for block order type 1 */
for (int ff1 = 0 ; ff1 < 2 ; ff1 ++)
{
for (int ff2 = 0 ; ff2 < 2; ff2++)
{
for (int ff3 = 0 ; ff3 < 2 ; ff3++)
{
int end1 = current_order[ii-1];
int end2 = current_order[ii];
int end3 = current_order[jj-1];
int end4 = current_order[jj];
if (ff1 == 1) end1 = current_order[0];
if (ff2 == 1) { end2 = current_order[jj-1]; end3 = current_order[ii];}
if (ff3 == 1) end4 = current_order[number_of_bins-1];
double current_edges_weight = pair_wise_distances[end1][end2] + pair_wise_distances[end3][end4];
if (lightest_edges_weight > current_edges_weight)
{
lightest_edges_weight = current_edges_weight;
block_order_type = 1;
if (ff1 == 0) flip_1 = false; else flip_1 = true;
if (ff2 == 0) flip_2 = false; else flip_2 = true;
if (ff3 == 0) flip_3 = false; else flip_3 = true;
}
}
}
}
/* for block order type 2 */
for (int ff1 = 0 ; ff1 < 2 ; ff1 ++)
{
for (int ff2 = 0 ; ff2 < 2; ff2++)
{
for (int ff3 = 0 ; ff3 < 2 ; ff3++)
{
int end1 = current_order[jj-1];
int end2 = current_order[0];
int end3 = current_order[ii-1];
int end4 = current_order[jj];
if (ff2 == 1) end1 = current_order[ii];
if (ff1 == 1) { end2 = current_order[ii-1]; end3 = current_order[0];}
if (ff3 == 1) end4 = current_order[number_of_bins-1];
double current_edges_weight = pair_wise_distances[end1][end2] + pair_wise_distances[end3][end4];
if (lightest_edges_weight > current_edges_weight)
{
lightest_edges_weight = current_edges_weight;
block_order_type = 2;
if (ff1 == 0) flip_1 = false; else flip_1 = true;
if (ff2 == 0) flip_2 = false; else flip_2 = true;
if (ff3 == 0) flip_3 = false; else flip_3 = true;
}
}
}
}
/* for block order type 3 */
for (int ff1 = 0 ; ff1 < 2 ; ff1 ++)
{
for (int ff2 = 0 ; ff2 < 2; ff2++)
{
for (int ff3 = 0 ; ff3 < 2 ; ff3++)
{
int end1 = current_order[ii-1];
int end2 = current_order[jj];
int end3 = current_order[number_of_bins-1];
int end4 = current_order[ii];
if (ff1 == 1) end1 = current_order[0];
if (ff3 == 1) { end2 = current_order[number_of_bins-1]; end3 = current_order[jj];}
if (ff2 == 1) end4 = current_order[jj-1];
double current_edges_weight = pair_wise_distances[end1][end2] + pair_wise_distances[end3][end4];
if (lightest_edges_weight > current_edges_weight)
{
lightest_edges_weight = current_edges_weight;
block_order_type = 3;
if (ff1 == 0) flip_1 = false; else flip_1 = true;
if (ff2 == 0) flip_2 = false; else flip_2 = true;
if (ff3 == 0) flip_3 = false; else flip_3 = true;
}
}
}
}
if (block_order_type == 1)
{
if (flip_1)
{
copy_order(current_order, tmp_storage,0,0,ii, false);
copy_order(tmp_storage,current_order,0,0,ii, true);
}
if (flip_2)
{
copy_order(current_order,tmp_storage,ii,ii,jj-ii, false);
copy_order(tmp_storage, current_order,ii,ii,jj-ii, true);
}
if (flip_3)
{
copy_order(current_order, tmp_storage,jj, jj, number_of_bins - jj, false);
copy_order(tmp_storage, current_order, jj, jj, number_of_bins - jj, true);
}
}
else if (block_order_type == 2)
{
copy_order(current_order,tmp_storage, 0 , 0, jj, false);
if (flip_1)
{
copy_order(tmp_storage, current_order,0,jj-ii,ii,true);
}
else
{
copy_order(tmp_storage, current_order,0,jj-ii,ii,false);
}
if (flip_2)
{
copy_order(tmp_storage, current_order,ii,0,jj-ii,true);
}
else
{
copy_order(tmp_storage, current_order,ii,0,jj-ii,false);
}
if (flip_3)
{
copy_order(current_order, tmp_storage,jj, jj, number_of_bins - jj, false);
copy_order(tmp_storage, current_order, jj, jj, number_of_bins - jj, true);
}
}
else if (block_order_type == 3)
{
if (flip_1)
{
copy_order(current_order, tmp_storage,0,0,ii,false);
copy_order(tmp_storage,current_order,0,0,ii,true);
}
copy_order(current_order,tmp_storage,ii,ii,number_of_bins-ii,false);
if (flip_2)
{
copy_order(tmp_storage, current_order, ii, number_of_bins - (jj-ii), jj - ii , true);
}
else
{
copy_order(tmp_storage, current_order, ii, number_of_bins - (jj-ii), jj - ii , false);
}
if (flip_3)
{
copy_order(tmp_storage, current_order, jj, ii, number_of_bins - jj, true);
}
else
{
copy_order(tmp_storage, current_order, jj, ii, number_of_bins - jj, false);
}
}
if (block_order_type != 0)
{
changed = true;
current_upper_bound = current_upper_bound + lightest_edges_weight - gone_edges_weight;
}
} // end for jj
} // end for ii
if(verbose_) {
cout << "current upper_bound op2:" << current_upper_bound << endl;
}
}//end while
changed = dis_locate();
if(verbose_) {
cout << "current upper_bound dislocation:" << current_upper_bound << endl;
}
}
} // end if
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
double MSTOpt::calculate_crt_upper_bound(){
double total_cost = 0.0;
for (int ii = 1; ii < number_of_bins; ii++) {
total_cost = total_cost + pair_wise_distances[current_order[ii]][current_order[ii - 1]];
}
return total_cost;
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
void MSTOpt::copy_order(vector<int> & order_from,
vector<int> & order_to,
int from_start_at,
int to_start_at,
int length,
bool change_orientation) {
if ( not change_orientation )
{
for (int ii = 0 ; ii < length; ii++)
{
order_to[to_start_at + ii] = order_from[from_start_at + ii];
}
}
else
{
for (int ii = 0 ; ii < length; ii++)
{
order_to[to_start_at + ii] = order_from[from_start_at + length - ii - 1];
}
}
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
bool MSTOpt::dis_locate()
{
/* first is a pointer to previous element, second is the pointer to the next element*/
//pair<int,int> crt_order[number_of_bins];
pair<int,int> * crt_order = new pair<int,int>[number_of_bins];
for (int ii = 0 ; ii < number_of_bins -1 ; ii++)
{
crt_order[current_order[ii]].second = current_order[ii+1];
}
crt_order[current_order[number_of_bins -1 ]].second = -1;
for (int ii = 1 ; ii < number_of_bins ; ii++)
{
crt_order[current_order[ii]].first = current_order[ii-1];
}
crt_order[current_order[0]].first = -1;
int header = current_order[0];
bool ever_changed = false;
bool changed = true;
while (changed)
{
changed = false;
/*try to relocate the node from everywhere to everywhere else*/
for (int ii = 0 ; ii < number_of_bins; ii ++)
{
double incre_cost_splicing = 0;
int previous = crt_order[ii].first;
int next = crt_order[ii].second;
if (previous != -1) {
incre_cost_splicing = incre_cost_splicing - pair_wise_distances[ii][previous];
}
if (next != -1 ) {
incre_cost_splicing = incre_cost_splicing - pair_wise_distances[ii][next];
}
if ((previous != -1) and (next != -1)) {
incre_cost_splicing = incre_cost_splicing + pair_wise_distances[previous][next];
}
int opt_pos = -1;
double incre_cost_insertion = 0;
if (header != ii) {
incre_cost_insertion = incre_cost_insertion + pair_wise_distances[ii][header];
}
else {
incre_cost_insertion = incre_cost_insertion + pair_wise_distances[ii][next];
}
for (int jj = 0 ; jj < number_of_bins; jj ++)
{
if ((jj != ii) and (jj != previous))
{
double tmp_cost = 0 ;
int jj_next = crt_order[jj].second;
tmp_cost = tmp_cost + pair_wise_distances[jj][ii];
if (jj_next != -1)
{
tmp_cost = tmp_cost + pair_wise_distances[ii][jj_next];
tmp_cost = tmp_cost - pair_wise_distances[jj][jj_next];
}
if (tmp_cost < incre_cost_insertion)
{
incre_cost_insertion = tmp_cost;
opt_pos = jj;
}
}
}
if ((incre_cost_insertion + incre_cost_splicing) < ZERO_MINUS )
{
/*Do the relocation*/
/*Do the splicing first*/
ever_changed = true;
changed = true;
if (previous != -1)
{
crt_order[previous].second = crt_order[ii].second;
}
if (next != -1)
{
crt_order[next].first = crt_order[ii].first;
}
if (previous == -1)
{
header = next;
}
/*Do the insertion next*/
if (opt_pos == -1)
{
crt_order[ii].second = header;
crt_order[ii].first = -1;
crt_order[header].first = ii;
header = ii;
}
else
{
int jj_next = crt_order[opt_pos].second;
crt_order[opt_pos].second = ii;
crt_order[ii].first = opt_pos;
crt_order[ii].second = jj_next;
if (jj_next != -1)
{
crt_order[jj_next].first = ii;
}
}
current_upper_bound = current_upper_bound + incre_cost_insertion + incre_cost_splicing;
}
}
};
current_order[0] = header;
int nxt_id = crt_order[header].second;
for (int ii = 1 ; ii < number_of_bins ; ii++)
{
current_order[ii] = nxt_id;
nxt_id = crt_order[nxt_id].second;
}
double crt_cost = calculate_crt_upper_bound();
assert(crt_cost < current_upper_bound + ZERO_PLUS);
assert(crt_cost > current_upper_bound - ZERO_PLUS);
delete [] crt_order;
return ever_changed;
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
vector<int> MSTOpt::get_the_longest_path()
{
vector<vector<int> > graph_MST(number_of_bins);
for (int ii = 1 ; ii < number_of_bins; ii++)
{
int jj = MST[ii];
graph_MST[ii].push_back(jj);
graph_MST[jj].push_back(ii);
}
vector<int> longest_path;
int longest_distance = -1;
/*Run BFS starting from every node*/
for (int ii = 0 ; ii < number_of_bins; ii ++)
{
vector<bool> visitted(number_of_bins, false);
vector<int> depth(number_of_bins, 0);
visitted[ii] = true;
vector<int> BFS_tree(number_of_bins);
BFS_tree[ii] = -1;
queue<int> fifoqueue;
int last_out = -1;
fifoqueue.push(ii);
while ( not fifoqueue.empty())
{
last_out = fifoqueue.front();
fifoqueue.pop();
for (vector<int>::iterator iter1 = (graph_MST[last_out]).begin();
iter1 != (graph_MST[last_out]).end();
iter1 ++ )
{
if (not visitted[*iter1])
{
fifoqueue.push(*iter1);
visitted[*iter1] = true;
depth[*iter1] = depth[last_out] + 1;
BFS_tree[*iter1] = last_out;
}
}
}
if (depth[last_out] > longest_distance)
{
longest_distance = depth[last_out];
longest_path.clear();
longest_path.push_back(last_out);
last_out = BFS_tree[last_out];
while (last_out != -1)
{
longest_path.push_back(last_out);
last_out = BFS_tree[last_out];
}
}
}
return longest_path;
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
double MSTOpt::new_serialization()
{
vector<int> longest_path = get_the_longest_path();
vector<pair<int,int> > crt_path(number_of_bins,make_pair(-1,-1));
if(verbose_){
cout << "the length of the longest path:" << longest_path.size() << endl;
}
int header;
header = longest_path[0];
crt_path[header].first=-1;
crt_path[header].second = -1;
int crt_node = header;
for ( int ii = 1; ii < longest_path.size(); ii++)
{
int jj = longest_path[ii];
crt_path[jj].first = crt_node;
crt_path[jj].second = -1;
crt_path[crt_node].second = jj;
crt_node = jj;
}
/*get the set of unvisitted nodes*/
vector<bool> visitted(number_of_bins, false);
for (int ii = 0 ; ii < longest_path.size(); ii ++)
{
visitted[longest_path[ii]] = true;
}
/*now, insert the unvisited nodes into the backbone one by one*/
for (int ii = 0 ; ii < number_of_bins; ii++)
{
if (visitted[ii] == false)
{
visitted[ii] = true;
double opt_cost = pair_wise_distances[ii][header] ;
int opt_posi = -1;
int crt_posi = header;
while (crt_posi != -1)
{
double tmp_cost;
tmp_cost = pair_wise_distances[crt_posi][ii];
int kk = crt_path[crt_posi].second;
if (kk != -1)
{
tmp_cost = tmp_cost + pair_wise_distances[ii][kk];
tmp_cost = tmp_cost - pair_wise_distances[crt_posi][kk];
}
if (tmp_cost < opt_cost)
{
opt_cost = tmp_cost;
opt_posi = crt_posi;
}
crt_posi = (crt_path[crt_posi]).second;
}
if (opt_posi == -1)
{
crt_path[ii].second = header;
crt_path[ii].first = -1;
crt_path[header].first = ii;
header = ii;
}
else
{
int kk = (crt_path[opt_posi]).second;
crt_path[ii].second = kk;
crt_path[ii].first = opt_posi;
crt_path[opt_posi].second = ii;
if (kk != -1)
{
crt_path[kk].first = ii;
}
}
}
}
current_order.resize(number_of_bins);
current_order[0] = header;
int crt_node_id = crt_path[header].second;
for (int ii = 1; ii < number_of_bins; ii ++)
{
current_order[ii] = crt_node_id;
crt_node_id = (crt_path[crt_node_id]).second;
}
current_upper_bound = 0 ;
for (int ii = 1 ; ii < number_of_bins; ii ++)
{
current_upper_bound = current_upper_bound + pair_wise_distances[current_order[ii]][current_order[ii-1]];
}
cost_after_initialization = current_upper_bound;
return current_upper_bound;
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
MSTOpt::Block_Chain MSTOpt::break_into_blocks(){
int bs = 0;
Block_Chain bc;
for (int ii = 1; ii < number_of_bins; ii++) {
// check the validity of the edge (current_order[ii], current_order[ii-1])
vector<int> nodes_before;
vector<int> nodes_after;
int first_node = current_order[ii - 1];
int second_node = current_order[ii];
double cost_of_edge = pair_wise_distances[first_node][second_node];
for (int jj = 0; jj < ii - 1; jj++) {
nodes_before.push_back(current_order[jj]);
}
for (int jj = ii + 1; jj < number_of_bins; jj++) {
nodes_after.push_back(current_order[jj]);
}
bool valid = true;
for (vector<int>::iterator iter1 = nodes_before.begin(); iter1 != nodes_before.end(); ++iter1) {
if (pair_wise_distances[*iter1][second_node] < cost_of_edge) {
valid = false;
break;
}
}
for (vector<int>::iterator iter1 = nodes_after.begin(); iter1 != nodes_after.end(); ++iter1) {
if (pair_wise_distances[first_node][*iter1] < cost_of_edge) {
valid = false;
break;
}
}
if (not valid) { // a new block
vector<int> block_markers;
for (int jj = bs; jj < ii; jj++) {
block_markers.push_back(current_order[jj]);
}
Block crt_block = {true, block_markers, static_cast<int>(block_markers.size()),
block_markers[0], block_markers[block_markers.size() - 1],
-1, -1};
bc.bs.push_back(crt_block);
bs = ii;
}
}
// assemble the last block
vector<int> last_block_markers;
for (int jj = bs; jj < number_of_bins; jj++) {
last_block_markers.push_back(current_order[jj]);
}
Block last_block = {true, last_block_markers,
static_cast<int>(last_block_markers.size()),
last_block_markers[0], last_block_markers[last_block_markers.size() - 1],
-1, -1};
bc.bs.push_back(last_block);
// do some correctness check
int total_bins = 0;
for (int ii = 0; ii < bc.bs.size(); ii++) {
total_bins = total_bins + bc.bs[ii].markers.size();
bc.bs[ii].p_b = ii - 1;
bc.bs[ii].n_b = ii + 1;
}
assert(total_bins == number_of_bins);
bc.bs[bc.bs.size() - 1].n_b = -1;
bc.header = 0;
return bc;
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
double MSTOpt::block_cost(const Block_Chain& bc){
double total_cost = 0.0;
int pre_block = bc.header;
int crt_block = bc.bs[pre_block].n_b;
while (crt_block != -1) {
int from = -1;
int to = -1;
if (bc.bs[pre_block].orientation) {
from = bc.bs[pre_block].last;
} else {
from = bc.bs[pre_block].first;
}
if (bc.bs[crt_block].orientation) {
to = bc.bs[crt_block].first;
} else {
to = bc.bs[crt_block].last;
}
total_cost = total_cost + pair_wise_distances[from][to];
pre_block = crt_block;
crt_block = bc.bs[crt_block].n_b;
}
return total_cost;
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
void MSTOpt::block_fix_orientation(Block_Chain& bc) {
bool changed = true;
double initial_cost = block_cost(bc);
double total_cost_reduction = 0.0;
while (changed) {
double cost_reduction_iter = 0.0;
int crt_index = bc.header;
while (crt_index != -1){
Block& crt_block = bc.bs[crt_index];
double cost_reduction = 0.0;
if (crt_block.p_b != -1) {
const Block& p_block = bc.bs[crt_block.p_b];
int from = -1;
if (p_block.orientation) {
from = p_block.last;
} else {
from = p_block.first;
}
if (crt_block.orientation) {
cost_reduction = cost_reduction + pair_wise_distances[from][crt_block.first] -
pair_wise_distances[from][crt_block.last];
} else {
cost_reduction = cost_reduction + pair_wise_distances[from][crt_block.last] -
pair_wise_distances[from][crt_block.first];
}
}
if (crt_block.n_b != -1) {
const Block& n_block = bc.bs[crt_block.n_b];
int to = -1;
if (n_block.orientation) {
to = n_block.first;
} else {
to = n_block.last;
}
if (crt_block.orientation) {
cost_reduction = cost_reduction + pair_wise_distances[to][crt_block.last] -
pair_wise_distances[to][crt_block.first];
} else {
cost_reduction = cost_reduction + pair_wise_distances[to][crt_block.first] -
pair_wise_distances[to][crt_block.last];
}
}
if (cost_reduction > 0.0) {
cost_reduction_iter = cost_reduction_iter + cost_reduction;
total_cost_reduction = total_cost_reduction + cost_reduction;
crt_block.orientation = (not crt_block.orientation);
}
crt_index = crt_block.n_b;
}
if (cost_reduction_iter > ZERO_PLUS) {
changed = true;
} else {
changed = false;
}
}
double new_cost = block_cost(bc);
assert(new_cost + total_cost_reduction < initial_cost + ZERO_PLUS);
assert(new_cost + total_cost_reduction > initial_cost - ZERO_PLUS);
if(verbose_) {
cout << "total cost reduction:" << total_cost_reduction << endl;
}
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
bool MSTOpt::block_optimize_iteration(Block_Chain& bc){
// try to relocate every block to everywhere else
// return true if this operation improves the order
int total_blocks = bc.bs.size();
if(verbose_){
cout << "number of blocks:" << total_blocks << endl;
}
if (total_blocks < 3) {
return false;
}
// print_bc(bc);
double original_cost = block_cost(bc);
double total_incremental_cost = 0.0;
vector<Block>& bs = bc.bs;
for (int ii = 0; ii < total_blocks; ii++) {
Block& crt_block = bs[ii];
double cost_reduction = 0.0;
// splice the block out of the chain
if (crt_block.n_b != -1) {
Block& next_block = bs[crt_block.n_b];
next_block.p_b = crt_block.p_b;
int from = -1;
int to = -1;
if (crt_block.orientation) {
from = crt_block.last;
} else {
from = crt_block.first;
}
if (next_block.orientation) {
to = next_block.first;
} else {
to = next_block.last;
}
cost_reduction = cost_reduction + pair_wise_distances[from][to];
}
if (crt_block.p_b != -1) {
Block& previous_block = bs[crt_block.p_b];
previous_block.n_b = crt_block.n_b;
int from = -1;
int to = -1;
if (previous_block.orientation) {
from = previous_block.last;
} else {
from = previous_block.first;
}
if (crt_block.orientation) {
to = crt_block.first;
} else {
to = crt_block.last;
}
cost_reduction = cost_reduction + pair_wise_distances[from][to];
}
if ((crt_block.n_b != -1) and (crt_block.p_b != -1)) {
Block& previous_block = bs[crt_block.p_b];
Block& next_block = bs[crt_block.n_b];
int from = -1;
int to = -1;
if (previous_block.orientation) {
from = previous_block.last;
} else {
from = previous_block.first;
}
if (next_block.orientation) {
to = next_block.first;
} else {
to = next_block.last;
}
cost_reduction = cost_reduction - pair_wise_distances[from][to];
}
if (ii == bc.header) {
bc.header = crt_block.n_b;
}
crt_block.p_b = -1;
crt_block.n_b = -1;
// cout << "one_block is spliced out" << endl;
// print_bc(bc);
// now try to find the optimum position for crt_block
// first try to put the block at the begining
int opt_pos = -1;
bool opt_orientation = true;
double opt_cost = numeric_limits<double>::max();
// compare two different orientations
int to = -1;
if (bs[bc.header].orientation) {
to = bs[bc.header].first;
} else {
to = bs[bc.header].last;
}
if (pair_wise_distances[crt_block.first][to] < pair_wise_distances[crt_block.last][to]) {
opt_cost = pair_wise_distances[crt_block.first][to];
opt_orientation = false;
} else {
opt_cost = pair_wise_distances[crt_block.last][to];
opt_orientation = true;
}
for (int jj = 0; jj < total_blocks; jj++) {
if (jj == ii) continue;
// check the forward direction first
double additional_cost1 = 0.0;
double additional_cost2 = 0.0;
Block& block_jj = bs[jj];
int from = -1;
if (block_jj.orientation) {
from = block_jj.last;
} else {
from = block_jj.first;
}
additional_cost1 = additional_cost1 + pair_wise_distances[from][crt_block.first];
additional_cost2 = additional_cost2 + pair_wise_distances[from][crt_block.last];
if (block_jj.n_b != -1) {
Block& next_jj = bs[block_jj.n_b];
int to = -1;
if (next_jj.orientation) {
to = next_jj.first;
} else {
to = next_jj.last;
}
additional_cost1 = additional_cost1 - pair_wise_distances[from][to];
additional_cost2 = additional_cost2 - pair_wise_distances[from][to];
additional_cost1 = additional_cost1 + pair_wise_distances[crt_block.last][to];
additional_cost2 = additional_cost2 + pair_wise_distances[crt_block.first][to];
}
bool jj_orientation = true;
double additional_cost;
if (additional_cost1 < additional_cost2) {
jj_orientation = true;
additional_cost = additional_cost1;
} else {
additional_cost = additional_cost2;
jj_orientation = false;
}
if (additional_cost < opt_cost) {
opt_cost = additional_cost;
opt_pos = jj;
opt_orientation = jj_orientation;
}
}
// now place crt_block to it's position
crt_block.orientation = opt_orientation;
if (opt_pos == -1) { // the block should be placed at the header of the chain
crt_block.n_b = bc.header;
bs[bc.header].p_b = ii;
bc.header = ii;
} else {
int next_pos = bs[opt_pos].n_b;
crt_block.n_b = next_pos;
bs[opt_pos].n_b = ii;
crt_block.p_b = opt_pos;
if (next_pos != -1) {
bs[next_pos].p_b = ii;
}
}
total_incremental_cost = total_incremental_cost + opt_cost - cost_reduction;
// cout << "the block has been put back" << endl;
// print_bc(bc);
}
double new_cost = block_cost(bc);
assert(new_cost < original_cost + total_incremental_cost + ZERO_PLUS);
assert(new_cost > original_cost + total_incremental_cost - ZERO_PLUS);
if(verbose_){
cout << "total incremental cost" << total_incremental_cost << endl;
}
if (total_incremental_cost < ZERO_MINUS) {
return true;
} else {
return false;
}
};
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
void MSTOpt::copy_over_order(const Block_Chain& bc){
int crt_block_id = bc.header;
int crt_marker_id = 0;
while (crt_block_id != -1){
const Block& crt_block = bc.bs[crt_block_id];
if (crt_block.orientation) {