- Added solutions by Ulrich Rieke.

2 files changed, 176 insertions, 0 deletions

diff --git a/challenge-101/ulrich-rieke/raku/ch-1.raku b/challenge-101/ulrich-rieke/raku/ch-1.raku
new file mode 100644
index 0000000000..a674de36c4
--- /dev/null
+++ b/challenge-101/ulrich-rieke/raku/ch-1.raku
@@ -0,0 +1,99 @@
+use v6 ;
+
+sub enterArray( ) {
+  say "Enter an array, items separated by blanks!" ;
+  my $line = $*IN.get ;
+  my @array = $line.split( /\s+/ ) ;
+  return @array ;
+}
+
+my @array = enterArray( ) ;
+#we fill the array with this value which is not in @array ;
+#this denotes that the field in the array wasn't visited yet ;
+my $stopvalue = prompt "Enter stop value!" ;
+my $len = @array.elems ;
+my $dima = floor( sqrt( $len ) ) ;
+if ( $len %% $dima ) {
+}
+else {
+  repeat {
+      $dima-- ;
+  } until ( $len %% $dima ) ;
+}
+my $dimb = $len div $dima ;
+my @spiralarray ; #will hold the items in a spiral
+#we fill @spiralarray with the stop value first
+for (0 .. $dima - 1 ) {
+  my $row ;
+  for (0 .. $dimb - 1 ) {
+      $row.push( $stopvalue ) ;
+  }
+  @spiralarray.push( $row ) ;
+}
+my @directions = ("right" , "up", "left" , "down" ) ;
+my $currentIndex = 0 ;#here we start in the array
+my $row = $dima - 1 ;#we fill the last row of the spiral array
+my $col = 0 ;#we start at column 0 , in the blocks, we use ++$col!
+my $diri = 0 ; #index into @directions, we begin with a rightwards move
+while ( $currentIndex < $len - 1) {
+  if ( @directions[ $diri ] eq "right" ) {
+      while (($col < $dimb - 1) and  (@spiralarray[ $row ][$col + 1]
+          == $stopvalue) and ($currentIndex < $len - 1 )) {
+    @spiralarray[$row][ $col++ ] = @array[$currentIndex++] ;
+      }
+      if (  $currentIndex == $len - 1 ) {
+    if ( $col <= $dimb - 1 and @spiralarray[ $row ][$col] ==
+          $stopvalue ) {
+        @spiralarray[$row][$col] = @array[ $currentIndex ] ;
+    }
+      }
+  }
+  elsif ( @directions[ $diri ] eq "down" ) {
+      while ( ($row < $dima - 1) and (@spiralarray[ $row + 1 ][ $col ] ==
+          $stopvalue ) and ( $currentIndex < $len - 1 ) ) {
+    @spiralarray[ $row++][ $col ] = @array[$currentIndex++] ;
+      }
+      if ( $currentIndex ==  $len - 1 ) {
+    if ( $row <= $dima - 1 and @spiralarray[ $row ][ $col ] ==
+          $stopvalue ) {
+        @spiralarray[$row][$col] = @array[ $currentIndex] ;
+    }
+      }
+  }
+  elsif ( @directions[ $diri ] eq "up" ) {
+      while ( ($row > 0 ) and ( @spiralarray[ $row - 1][$col] ==
+          $stopvalue ) and ( $currentIndex < $len - 1 )) {
+        @spiralarray[$row--][$col] = @array[$currentIndex++] ;
+      }
+      if ( $currentIndex == $len - 1 ) {
+    if ( $row >= 0 and @spiralarray[ $row ][ $col ] ==
+          $stopvalue ) {
+        @spiralarray[ $row ][ $col ] = @array[ $currentIndex] ;
+    }
+      }
+  }
+  elsif ( @directions[ $diri ] eq "left" ) {
+      while (($col > 0 ) and (@spiralarray[ $row ][$col - 1 ] ==
+          $stopvalue ) and ( $currentIndex < $len - 1 ) ) {
+    @spiralarray[$row][$col--] = @array[$currentIndex++] ;
+      }
+      if (  $currentIndex == $len - 1 ) {
+    if ( $col >= 0 and @array[ $row ][ $col ] == $stopvalue ) {
+        @spiralarray[$row][$col] = @array[ $currentIndex ] ;
+    }
+      }
+  }
+  $diri++ ;
+  $diri = $diri % 4 ;
+}
+my @sorted = @array.sort( {~$^b.chars <=> ~$^a.chars} ) ;
+my $maxwidth = @sorted[0].chars ;
+for (0 .. $dima - 1 ) -> $i {
+  for ( 0 .. $dimb - 1 ) -> $j {
+      my $num = @spiralarray[$i][$j] ;
+      my $width = $num.Str.chars ;
+      print ' ' x ( $maxwidth - $width + 1) ;
+      print $num ;
+  }
+  print "\n" ;
+}
diff --git a/challenge-101/ulrich-rieke/raku/ch-2.raku b/challenge-101/ulrich-rieke/raku/ch-2.raku
new file mode 100644
index 0000000000..9ab076efa6
--- /dev/null
+++ b/challenge-101/ulrich-rieke/raku/ch-2.raku
@@ -0,0 +1,77 @@
+use v6 ;
+
+sub enterPoints( ) {
+  my @points ;
+  for (1 .. 3) {
+      say "Enter point coordinates, separated by a blank!" ;
+      my $line = $*IN.get ;
+      my @coordinates = $line.split( /\s+/ ) ;
+      @points.push( [|@coordinates] ) ;
+  }
+  return @points ;
+}
+
+sub findEquation( [$x1, $y1] , [$x2, $y2] ) {
+  my $m ;
+  my $b ;
+  if ( $x1 != $x2 ) {
+      $m = ($y1 -$y2) / ($x1 - $x2) ;
+  }
+  if ( $m.defined ) {
+      $b = $y1 - $m * $x1 ;
+  }
+  if ( $m.defined and $b.defined ) {
+      return ( $m, $b ) ;
+  }
+  else {
+      return ( ) ;
+  }
+}
+
+my @points = enterPoints( ) ;
+my $output = 0 ;
+#a point lies inside the triangle if we can add 2 vectors which
+#are parallel to BA and to CA so that the ratios of the vectors to
+#BA ( w1 ) and to CA (w2) are both positive and add up to a number
+#not larger than 1
+#point P is inside the triangle if the following equation holds true:
+#P = A + w1( B - A ) + w2( C - A )
+#we need 2 equations to find w1 and w2, and we use the corresponding
+#equation for the x and y coordinate for that.
+#by solving this by hand, we get this for w1:
+#w1 =  (Ax(Cy -Ay) + (Py -Ay )(Cx - Ax)- Px(Cy -Ay )) /
+#      ((By -Ay )( Cx - Ax ) - (Bx -Ax ) (Cy -Ay))
+#w2 can be obtained by entering w1 into:
+#w2 = (Py -Ay -w1(By -Ay)) / (Cy -Ay )
+my $w1 = (@points[0][0] * ( @points[2][1] - @points[0][1] ) +
+      (0 - @points[0][1] ) * (@points[2][0] - @points[0][0] )) /
+      ((@points[1][1] - @points[0][1]) - (@points[1][0] - @points[0][0] )
+      * (@points[2][1] - @points[0][1] )) ;
+my $w2 = (-@points[0][1] - $w1 * (@points[1][1] - @points[0][1])) /
+  (@points[2][1] - @points[0][1] ) ;
+if ( $w1 >= 0 and $w2 >= 0 and ($w1 + $w2) <= 1 ) {
+  $output = 1 ;
+}
+else {#it might be on the edge and not inside !
+  my @equations ;
+  my @result = findEquation( @points[0] , @points[1] ) ;
+  if ( @result ) {
+      @equations.push( [|@result] ) ;
+  }
+  @result = findEquation( @points[1] , @points[2] ) ;
+  if ( @result ) {
+      @equations.push( [|@result] ) ;
+  }
+  @result = findEquation( @points[0] , @points[2] ) ;
+  if ( @result ) {
+      @equations.push( [|@result] ) ;
+  }
+  for @equations -> $res {
+#we have to check y = mx + b ; with y = 0 and x = 0, only b == 0 is required
+      if ( $res[1] == 0 ) { #it's on the edge!
+    $output = 1 ;
+    last ;
+      }
+  }
+}
+say $output ;