BK-Tree Implementation Insertion time is more how to reduce - c++

Question

Following is my attempt to write BK-Tree , for 150000 word file it takes around 8 seconds
Is there any way to reduce this time.
Following is my code
#include <stdio.h>
#include <string>
#include <vector>
#include <fstream>
#include <iostream>
#include <sstream>
#include "Timer.h"
class BkTree {
public:
BkTree();
~BkTree();
void insert(std::string m_item);
private:
size_t EditDistance( const std::string &s, const std::string &t );
struct Node {
std::string m_item;
size_t m_distToParent;
Node *m_firstChild;
Node *m_nextSibling;
Node(std::string x, size_t dist);
~Node();
};
Node *m_root;
int m_size;
protected:
};
BkTree::BkTree() {
m_root = NULL;
m_size = 0;
}
BkTree::~BkTree() {
if( m_root )
delete m_root;
}
BkTree::Node::Node(std::string x, size_t dist) {
m_item = x;
m_distToParent = dist;
m_firstChild = m_nextSibling = NULL;
}
BkTree::Node::~Node() {
if( m_firstChild )
delete m_firstChild;
if( m_nextSibling )
delete m_nextSibling;
}
void BkTree::insert(std::string m_item) {
if( !m_root ){
m_size = 1;
m_root = new Node(m_item, -1);
return;
}
Node *t = m_root;
while( true ) {
size_t d = EditDistance( t->m_item, m_item );
if( !d )
return;
Node *ch = t->m_firstChild;
while( ch ) {
if( ch->m_distToParent == d ) {
t = ch;
break;
}
ch = ch->m_nextSibling;
}
if( !ch ) {
Node *newChild = new Node(m_item, d);
newChild->m_nextSibling = t->m_firstChild;
t->m_firstChild = newChild;
m_size++;
break;
}
}
}
size_t BkTree::EditDistance( const std::string &left, const std::string &right ) {
size_t asize = left.size();
size_t bsize = right.size();
std::vector<size_t> prevrow(bsize+1);
std::vector<size_t> thisrow(bsize+1);
for(size_t i = 0; i <= bsize; i++)
prevrow[i] = i;
for(size_t i = 1; i <= asize; i ++) {
thisrow[0] = i;
for(size_t j = 1; j <= bsize; j++) {
thisrow[j] = std::min(prevrow[j-1] + size_t(left[i-1] != right[j-1]),
1 + std::min(prevrow[j],thisrow[j-1]) );
}
std::swap(thisrow,prevrow);
}
return prevrow[bsize];
}
void trim(std::string& input_str) {
if(input_str.empty()) return;
size_t startIndex = input_str.find_first_not_of(" ");
size_t endIndex = input_str.find_last_not_of("\r\n");
std::string temp_str = input_str;
input_str.erase();
input_str = temp_str.substr(startIndex, (endIndex-startIndex+ 1) );
}
int main( int argc, char **argv ) {
BkTree *pDictionary = new BkTree();
std::ifstream dictFile("D:\\dictionary.txt");
Timer *t = new Timer("Time Taken to prepare Tree = ");
std::string line;
if (dictFile.is_open()) {
while (! dictFile.eof() ) {
std::getline (dictFile,line);
trim(line);
pDictionary->insert(line);
}
dictFile.close();
}
delete t;
delete pDictionary;
return 0;
}
class Timer {
public:
Timer (const std::string &name = "undef");
~Timer (void);
private:
std::string m_name;
std::clock_t m_started;
protected:
};
Timer::Timer (const std::string &name) : m_name(name), m_started(clock()) {
}
Timer::~Timer (void) {
double secs = static_cast<double>(std::clock() - m_started) / CLOCKS_PER_SEC;
std::cout << m_name << ": " << secs << " secs." << std::endl;
}

Answer 1

You can reduce the time by eliminating the I/O. To test your algorithm, remove as many objects out of the equation that are not directly under the control of your program. For example, the OS controls the I/O, it is out of your control. An array of constant text removes much OS involvement (the OS still may page the array depending on OS memory allocation).
Next, most tree structures are data oriented. Their performance times depend on the data. Try three sets of data: sorted ascending, "random", and sorted descending. Note the times for each.
Look at your loops and factor out any constants. Create temporary variables in loops for constant calculations in inner loops. Remove unnecessary operations.
Lastly, if your program and algorithm is very robust, work on other projects. Optimize only if necessary.