- Added solutions by Ulrich Rieke.

5 files changed, 201 insertions, 0 deletions

diff --git a/challenge-055/ulrich-rieke/cpp/ch-2.cpp b/challenge-055/ulrich-rieke/cpp/ch-2.cpp
new file mode 100644
index 0000000000..10adfc4756
--- /dev/null
+++ b/challenge-055/ulrich-rieke/cpp/ch-2.cpp
@@ -0,0 +1,67 @@
+#include <iostream>
+#include <vector>
+#include <iterator>
+#include <algorithm>
+#include <utility>
+#include <cstdlib>
+
+//this function creates pairs of neighbouring numbers in a vector
+std::vector<std::pair<int, int>> createDoublets ( const std::vector<int> & numbers ) {
+  std::vector<std::pair<int , int>> doublets ;
+  int len = numbers.size( ) ;
+  for ( int i = 0 ; i < len - 1 ; i++ ) {
+      std::pair<int , int> p { *(numbers.begin( ) + i ) ,
+        *(numbers.begin( ) + i + 1 ) } ;
+      doublets.push_back( p ) ;
+  }
+  return doublets ;
+}
+
+//in order to create a "wavy list of numbers", a vector of numbers is
+//converted into a vector of pairs of neighbouring numbers. To be wavy,
+//even-indexed pairs must be descending, odd-indexed ones must ascend.
+//if this holds true for all pairs a permutation is "wavy"
+bool myCondition( const std::vector<int> & numbers ) {
+  std::vector<std::pair<int, int>> doublets { createDoublets( numbers ) } ;
+  int len = doublets.size( ) ;
+  std::vector<bool> validWavy ;
+  for (int i = 0 ; i < len ; i++ ) {
+      std::pair<int , int> p = doublets[ i ] ;
+      validWavy.push_back (( i % 2 == 0 ) && ( p.first >= p.second ) ) ;
+      validWavy.push_back (( i % 2 == 1 ) && ( p.first <= p.second ) ) ;
+  }
+  int i = 0 ;
+  for ( auto b : validWavy ) {
+      if ( b )
+    i++ ;
+  }
+  return ( i == len ) ;
+}
+
+//numbers are entered as arguments on the command line. A minimum number
+//of 2 is desirable and requested
+int main( int argc, char * argv[] ) {
+  std::vector<int> input ;
+  if ( argc < 3 ) {
+      std::cout << "There is little sense in permuting such short sequences!\n" ;
+      return 1 ;
+  }
+  for ( int i = 1 ; i < argc ; i++ ) {
+      input.push_back( std::atoi( argv[ i ] ) ) ;
+  }
+  std::vector<std::vector<int>> permus ;
+  std::vector<std::vector<int>> wavies ;
+  do {
+      permus.push_back( input ) ;
+  } while ( std::next_permutation( input.begin( ) , input.end( ) )) ;
+  std::copy_if( permus.begin( ) , permus.end( ) ,
+    std::back_inserter( wavies ) , myCondition ) ;
+  for ( auto & it : wavies ) {
+      std::cout << "[ " ;
+      for ( int i : it ) {
+    std::cout << i << " " ;
+      }
+      std::cout << " ]\n" ;
+  }
+  return 0 ;
+}
diff --git a/challenge-055/ulrich-rieke/haskell/ch-2.hs b/challenge-055/ulrich-rieke/haskell/ch-2.hs
new file mode 100644
index 0000000000..b87dbe4034
--- /dev/null
+++ b/challenge-055/ulrich-rieke/haskell/ch-2.hs
@@ -0,0 +1,16 @@
+module Challenge055_2
+  where
+import Data.List.Split ( divvy )
+import Data.List ( permutations , (!!) )
+
+wavyLists :: [Int] -> [[Int]]
+wavyLists list = filter myCondition $ permutations list
+
+myCondition :: [Int] -> Bool
+myCondition sublist = all numbersteps $ zip doublets [0,1..]
+where
+  doublets = divvy 2 1 sublist
+  numbersteps :: ([Int] , Int ) -> Bool
+  numbersteps ( li , num )
+  |even num = li !! 0 >= li !! 1
+  |odd num  = li !! 0 <= li !! 1
diff --git a/challenge-055/ulrich-rieke/perl/ch-1.pl b/challenge-055/ulrich-rieke/perl/ch-1.pl
new file mode 100644
index 0000000000..0496f5a6da
--- /dev/null
+++ b/challenge-055/ulrich-rieke/perl/ch-1.pl
@@ -0,0 +1,55 @@
+#!/usr/bin/perl ;
+use strict ;
+use warnings ;
+use POSIX qw ( floor ) ;
+
+sub toBinary {
+  my $num = shift ;
+  my @nums ;
+  while ( $num != 0 ) {
+      my $remainder = $num % 2 ;
+      push @nums, $remainder ;
+      $num = floor ( $num / 2 ) ;
+  }
+  return reverse @nums ;
+}
+
+sub countChars {
+  my $string = shift ;
+  my $searched = shift ;
+  return scalar ( grep { $_ eq $searched } split ( // , $string ) ) ;
+}
+
+sub myFlip {
+  my $string = shift ;
+  my $len = length $string ;
+  for my $i ( 0..$len - 1) {
+      if ( substr( $string , $i , 1 ) eq "1" ) {
+    substr( $string , $i , 1 ) = "0" ;
+      }
+      else {
+    substr( $string , $i , 1 ) = "1" ;
+      }
+  }
+  return $string ;
+}
+
+my @flippedArrs ;
+my @digits = toBinary ( $ARGV[0] ) ;
+my $len = scalar @digits ;
+my $binary = join ( '' , @digits ) ;
+for my $l (0 .. $len - 1 ) {
+  for my $r ( $l .. $len - 1 ) {
+      my $flipped = substr( $binary , 0 , $l ) .
+    myFlip( substr( $binary , $l , $r - $l ) ) .
+    substr ( $binary, $r ) ;
+      push @flippedArrs, [ $l , $r , countChars( $flipped , "1" ) ] ;
+  }
+}
+my @sorted = sort { ${$b}[2] <=> ${$a}[2] } @flippedArrs ;
+print ("L " . $sorted[0][0] . " , R " . $sorted[0][1] . "\n" ) ;
+my $i = 1 ;
+while ( $sorted[ $i ][ 2 ] == $sorted[ 0 ][ 2 ] ) {
+  print ("L " . $sorted[$i][0] . " , R " . $sorted[$i][1] . "\n") ;
+  $i++ ;
+}
diff --git a/challenge-055/ulrich-rieke/raku/ch-1.p6 b/challenge-055/ulrich-rieke/raku/ch-1.p6
new file mode 100644
index 0000000000..2537ea0e47
--- /dev/null
+++ b/challenge-055/ulrich-rieke/raku/ch-1.p6
@@ -0,0 +1,36 @@
+use v6 ;
+
+sub myFlip( Str $n --> Str ) {
+  return $n.comb.map( { $_ eq "1" ?? "0" !! "1" } ).join ;
+}
+
+sub countChar( Str $string , Str $searched --> Int ) {
+  return $string.comb.grep( {$_ eq $searched} ).elems ;
+}
+
+sub MAIN( Int $num ) {
+  my $binary = $num.base( 2 ).Str ;
+  $binary.say ;
+  my $len = $binary.chars ;
+  my @pairs ;
+  for (0..$len - 1 ) -> $l {
+      for ( $l..$len - 1 ) -> $r {
+    my $flipped = $binary.substr(0 , $l ) ~
+        myFlip( $binary.substr( $l, $r - $l ) ) ~
+        $binary.substr( $r ) ;
+    @pairs.push( ( $l , $r , $flipped ) ) ;
+      }
+  }
+  my @changedPairs ;
+  for @pairs <-> $element {
+      @changedPairs.push( ( $element[ 0 ] , $element[ 1] ,
+          countChar( $element[ 2] , "1" ) ) ) ;
+  }
+  my @sorted = @changedPairs.sort( { $^b[ 2 ] <=> $^a[ 2 ] } ) ;
+  say "L {@sorted[0][0] } , R { @sorted[0][1 ] }" ;
+  my $i = 1 ;
+  while ( @sorted[ $i ][2] == @sorted[ 0 ][ 2 ] ) {
+      say "L {@sorted[$i][0] } , R { @sorted[$i][1 ] }" ;
+      $i++ ;
+  }
+}
diff --git a/challenge-055/ulrich-rieke/raku/ch-2.p6 b/challenge-055/ulrich-rieke/raku/ch-2.p6
new file mode 100644
index 0000000000..c247e6c2f5
--- /dev/null
+++ b/challenge-055/ulrich-rieke/raku/ch-2.p6
@@ -0,0 +1,27 @@
+use v6 ;
+
+sub myCondition( @array --> Bool ) {
+  my @doublets = @array.rotor(2 => -1) ;
+  my $len = @doublets.elems ;
+  my @trues ;
+  for (0..$len - 1 ) -> $i {
+      if ( $i %% 2 ) {
+    @trues.push( @doublets[$i][0] >= @doublets[$i][1] ) ;
+      }
+      else {
+    @trues.push( @doublets[$i][ 0 ] <= @doublets[$i][ 1 ] ) ;
+      }
+  }
+  return @trues.grep( { $_ == True } ).elems == $len ;
+}
+
+sub MAIN( ) {
+  my $num ;
+  my @theArray ;
+  $num = prompt "Enter a number (negative number to stop) : " ;
+  while ( $num > 0 ) {
+      @theArray.push( $num ) ;
+      $num = prompt "next number! " ;
+  }
+  .say for @theArray.permutations.grep( { myCondition( @_) } ) ;
+}