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#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <map>
#include <queue>
#include <algorithm>
#include <ctime>
using namespace std;
vector<string> readWords( istream & in )
{
string oneLine;
vector<string> v;
while( in >> oneLine )
v.push_back( oneLine );
return v;
}
// Returns true if word1 and word2 are the same length
// and differ in only one character.
bool oneCharOff( const string & word1, const string & word2 )
{
if( word1.length( ) != word2.length( ) )
return false;
int diffs = 0;
for( int i = 0; i < word1.length( ); ++i )
if( word1[ i ] != word2[ i ] )
if( ++diffs > 1 )
return false;
return diffs == 1;
}
// Computes a map in which the keys are words and values are vectors of words
// that differ in only one character from the corresponding key.
// Uses a quadratic algorithm, but speeds things up a little by
// maintaining an additional map that groups words by their length.
map<string,vector<string>>
computeAdjacentWords( const vector<string> & words )
{
map<string,vector<string>> adjWords;
map<int,vector<string>> wordsByLength;
// Group the words by their length
for( auto & thisWord : words )
wordsByLength[ thisWord.length( ) ].push_back( thisWord );
// Work on eaach group separately
for( auto & entry : wordsByLength )
{
const vector<string> & groupsWords = entry.second;
for( int i = 0; i < groupsWords.size( ); ++i )
for( int j = i + 1; j < groupsWords.size( ); ++j )
if( oneCharOff( groupsWords[ i ], groupsWords[ j ] ) )
{
adjWords[ groupsWords[ i ] ].push_back( groupsWords[ j ] );
adjWords[ groupsWords[ j ] ].push_back( groupsWords[ i ] );
}
}
return adjWords;
}
// Find most changeable word: the word that differs in only one
// character with the most words. Return a list of these words, in case of a tie.
vector<string>
findMostChangeable( const map<string,vector<string>> & adjacentWords )
{
vector<string> mostChangeableWords;
int maxNumberOfAdjacentWords = 0;
for( auto & entry : adjacentWords )
{
const vector<string> & wordList = entry.second;
if( wordList.size( ) > maxNumberOfAdjacentWords )
{
maxNumberOfAdjacentWords = wordList.size( );
mostChangeableWords.clear( );
}
if( wordList.size( ) == maxNumberOfAdjacentWords )
mostChangeableWords.push_back( entry.first );
}
return mostChangeableWords;
}
void printMostChangeables( const vector<string> & mostChangeable,
const map<string,vector<string>> & adjWords )
{
auto & adjacentWords = const_cast<map<string,vector<string>> &>( adjWords );
for( auto & thisWord : mostChangeable )
{
cout << thisWord << ":";
vector<string> & adjacents = adjacentWords[ thisWord ];
for( string & str : adjacents )
cout << " " << str;
cout << " (" << adjacents.size( ) << " words)" << endl;
}
}
void printHighChangeables( const map<string,vector<string>> & adjacentWords,
int minWords = 15 )
{
for( auto & entry : adjacentWords )
{
const vector<string> & words = entry.second;
if( words.size( ) >= minWords )
{
cout << entry.first << " (" << words.size( ) << "):";
for( auto & str : words )
cout << " " << str;
cout << endl;
}
}
}
int main( )
{
clock_t start, end;
ifstream fin( "words.txt" );
vector<string> words = readWords( fin );
cout << "Read the words..." << words.size( ) << endl;
map<string,vector<string> > adjacentWords;
start = clock( );
adjacentWords = computeAdjacentWords( words );
end = clock( );
cout << "Elapsed time FAST: " << double(end-start)/CLOCKS_PER_SEC << endl;
cout << "Adjacents computed.." << endl;
vector<string> mostChangeable = findMostChangeable( adjacentWords );
cout << "Most changeable computed..." << endl;
printMostChangeables( mostChangeable, adjacentWords );
return 0;
}
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