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#include <iostream>
#include <vector>
#include <string>
#include <map>
#include <sstream>
#include <cstdlib>
#include <algorithm>
std::vector<std::string> split( const std::string & text , char delimiter ) {
std::istringstream istr { text } ;
std::string word ;
std::vector<std::string> words ;
while ( std::getline( istr , word , delimiter ) ) {
words.push_back( word ) ;
}
return words ;
}
//create all fields of a chess board
std::vector<std::string> findAllFields( ) {
std::string cols {"abcdefgh"} ;
std::string rows {"12345678"} ;
std::vector<std::string> board ;
for ( int i = 0 ; i < cols.length( ) ; i++ ) {
for ( int j = 0 ; j < rows.length( ) ; j++ ) {
std::string field { cols.substr( i , 1 ).append( rows.substr( j , 1 ) ) } ;
board.push_back( field ) ;
}
}
return board ;
}
//all suitable fields on a chessboard are those that differ from the given field
// by an absolute difference of 2 in rows and of 1 in columns or vice versa
std::vector<std::string> findTargets( const std::string & field , const
std::vector<std::string> & board ) {
std::vector<std::string> selected ;
static const std::string columns {"abcdefgh"} ;
static const std::string rows {"12345678"} ;
auto selector = [field]( const auto & f ) {
auto colfound = columns.find_first_of( field.substr( 0 , 1 ) ) ;
auto rowfound = rows.find_first_of( field.substr( 1 , 1 ) ) ;
auto fieldcol = columns.find_first_of( f.substr( 0 , 1 ) ) ;
auto fieldrow = rows.find_first_of( f.substr( 1 , 1 ) ) ;
auto coldiff = abs( colfound - fieldcol ) ;
auto rowdiff = abs( rowfound - fieldrow ) ;
return ( (coldiff == 1) && (rowdiff == 2)) || ( (coldiff == 2) &&
(rowdiff == 1 )) ;
} ;
std::copy_if( board.begin( ) , board.end( ) , std::back_inserter( selected ) ,
selector ) ;
return selected ;
}
int main( ) {
std::cout << "Enter a source and a target field!\n" ;
std::string line ;
std::getline( std::cin, line ) ;
std::vector<std::string> fields { split( line , ' ' ) } ;
std::vector<std::string> chessboard { findAllFields( ) } ;
std::string sourceField { fields[ 0 ] } ;
std::string targetField { fields[ 1 ] } ;
std::vector<std::string> targets = findTargets( sourceField , chessboard ) ;
int count = 1 ;
while ( std::find( targets.begin( ) , targets.end( ) , targetField ) ==
targets.end( ) ) {
count++ ;
std::vector<std::string> newTargets , elementTargets ;
for ( auto it = targets.begin( ) ; it != targets.end( ) ; it++ ) {
elementTargets = findTargets( *it , chessboard ) ;
for ( auto f : elementTargets )
newTargets.push_back( f ) ;
elementTargets.clear( ) ;
}
for ( auto f : newTargets )
targets.push_back( f ) ;
}
std::cout << count << '\n' ;
return 0 ;
}
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