- Added solutions by Eric Cheung.

- Added solutions by Thomas Kohler.
- Added solutions by PokGoPun.
- Added solutions by Mark Anderson.
- Added solutions by Feng Chang.
- Added solutions by E. Choroba.

36 files changed, 3519 insertions, 3113 deletions

diff --git a/challenge-277/luca-ferrari/pljava/pom.xml b/challenge-277/luca-ferrari/pljava/pom.xml
index ab36c0045b..1ed95c5978 100644
--- a/challenge-277/luca-ferrari/pljava/pom.xml
+++ b/challenge-277/luca-ferrari/pljava/pom.xml
@@ -7,14 +7,14 @@
 
   <groupId>PWC</groupId>
   <artifactId>
-    PWC276
+    PWC277
   </artifactId>
   <version>
     1
   </version>
 
-  <name>Perl Weekly Challenge 276 with package PWC276</name>
-  <description>Implementation of the tasks in PL/Java for PWC 276</description>
+  <name>Perl Weekly Challenge 277 with package PWC277</name>
+  <description>Implementation of the tasks in PL/Java for PWC 277</description>
 
   <properties>
     <project.build.sourceEncoding>US-ASCII</project.build.sourceEncoding>
diff --git a/challenge-277/luca-ferrari/pljava/src/main/java/Task1.java b/challenge-277/luca-ferrari/pljava/src/main/java/Task1.java
new file mode 100644
index 0000000000..157decedd7
--- /dev/null
+++ b/challenge-277/luca-ferrari/pljava/src/main/java/Task1.java
@@ -0,0 +1,27 @@
+public static int task1_pljava( String[] words1, String[] words2 ) throws SQLException {
+    logger.log( Level.INFO, "Entering pwc277.task1_pljava" );
+
+    final Map<String, Integer[]> counting = new HashMap<String, Integer[]>();
+
+    Stream.of( words1 ).forEach( current -> {
+    	Integer[] count = { 0, 0 };
+    	counting.putIfAbsent( current, count );
+    	count = counting.get( current );
+    	count[ 0 ]++;
+    	counting.put( current, count );
+    } );
+
+
+    Stream.of( words2 ).forEach( current -> {
+    	Integer[] count = { 0, 0 };
+    	counting.putIfAbsent( current, count );
+    	count = counting.get( current );
+    	count[ 1 ]++;
+    	counting.put( current, count );
+    } );
+
+    return (int) counting.entrySet().stream().filter( current -> {
+    	Integer[] count = current.getValue();
+    	return count[ 0 ] == count[ 1 ] && count[ 0 ] == 1;
+    } ).count();
+}
diff --git a/challenge-277/luca-ferrari/pljava/src/main/java/Task2.java b/challenge-277/luca-ferrari/pljava/src/main/java/Task2.java
new file mode 100644
index 0000000000..87c0dde2d0
--- /dev/null
+++ b/challenge-277/luca-ferrari/pljava/src/main/java/Task2.java
@@ -0,0 +1,15 @@
+public static final int task2_pljava( int[] numbers ) throws SQLException {
+    logger.log( Level.INFO, "Entering pwc277.task2_pljava" );
+
+    final int[] c = new int[]{ 0 };
+    IntStream.range( 0, numbers.length - 1 )
+        .forEach( i -> {
+    	    c[ 0 ] += IntStream.range( i + 1, numbers.length )
+    		.filter( j -> {
+    			return numbers[ i ] != numbers[ j ]
+    			    && Math.abs( numbers[ i ] - numbers[ j ] ) < Math.min( numbers[ i ], numbers[ j ] );
+    		    } ).count();
+    	} );
+
+    return c[ 0 ];
+}
diff --git a/challenge-277/luca-ferrari/plperl/ch-1.plperl b/challenge-277/luca-ferrari/plperl/ch-1.plperl
new file mode 100644
index 0000000000..b3e94089f6
--- /dev/null
+++ b/challenge-277/luca-ferrari/plperl/ch-1.plperl
@@ -0,0 +1,28 @@
+CREATE OR REPLACE FUNCTION
+pwc277.task1_plperl( text[], text[] )
+RETURNS int
+AS $CODE$
+
+   my ( $left, $right ) = @_;
+
+   my @single_left;
+   my @single_right;
+
+   for my $word ( $left->@* ) {
+       push @single_left, $word  if ( scalar( grep { $_ eq $word } $left->@* ) == 1 );
+   }
+
+   for my $word ( $right->@* ) {
+       push @single_right, $word  if ( scalar( grep { $_ eq $word } $right->@* ) == 1 );
+   }
+
+   my $counter = 0;
+   for my $word ( @single_left ) {
+       $counter++ if ( grep { $_ eq $word } @single_right );
+   }
+
+   return $counter;
+
+$CODE$
+LANGUAGE plperl;
+
diff --git a/challenge-277/luca-ferrari/plperl/ch-2.plperl b/challenge-277/luca-ferrari/plperl/ch-2.plperl
new file mode 100644
index 0000000000..b483cec8b0
--- /dev/null
+++ b/challenge-277/luca-ferrari/plperl/ch-2.plperl
@@ -0,0 +1,30 @@
+CREATE OR REPLACE FUNCTION
+pwc277.task2_plperl( int[] )
+RETURNS int
+AS $CODE$
+
+   my ( $nums ) = @_;
+   my @strong;
+
+   my $abs = sub {
+      return $_[ 0 ] * - 1 if ( $_[ 0 ] < 0 );
+      return $_[ 0 ];
+   };
+
+   my $min = sub {
+      return $_[ 0 ] if ( $_[ 0 ] < $_[ 1 ] );
+      return $_[ 1 ];
+   };
+
+   for my $i ( 0 .. $nums->@* - 2 ) {
+       for my $j ( $i + 1 .. $nums->@* - 1 ) {
+              my ( $left, $right ) = ( $nums->@[ $i ], $nums->@[ $j ] );
+    	   push @strong, [ $left, $right ]  if ( $abs->( $left - $rigth ) > 0 && $abs->( $left - $right ) < $min->( $left, $right ) );
+       }
+   }
+
+   return scalar( @strong );
+
+$CODE$
+LANGUAGE plperl;
+
diff --git a/challenge-277/luca-ferrari/plpgsql/ch-1.sql b/challenge-277/luca-ferrari/plpgsql/ch-1.sql
new file mode 100644
index 0000000000..70bfb4aab7
--- /dev/null
+++ b/challenge-277/luca-ferrari/plpgsql/ch-1.sql
@@ -0,0 +1,25 @@
+CREATE OR REPLACE FUNCTION
+pwc277.task1_plpgsql( words1 text[], words2 text[] )
+RETURNS int
+AS $CODE$
+
+   WITH w1 AS (
+       SELECT w::text
+    FROM unnest( words1 ) w
+    GROUP BY w
+    HAVING count(*) = 1
+  ),
+  w2 AS (
+         SELECT w::text
+    FROM unnest( words2 ) w
+    GROUP BY w
+    HAVING count(*) = 1
+  )
+  SELECT count( l.w )
+  FROM w1 l, w2 r
+  WHERE l.w = r.w
+
+$CODE$
+LANGUAGE sql;
+
+
diff --git a/challenge-277/luca-ferrari/plpgsql/ch-2.sql b/challenge-277/luca-ferrari/plpgsql/ch-2.sql
new file mode 100644
index 0000000000..84f99da312
--- /dev/null
+++ b/challenge-277/luca-ferrari/plpgsql/ch-2.sql
@@ -0,0 +1,28 @@
+CREATE OR REPLACE FUNCTION
+pwc277.task2_plpgsql( nums int[] )
+RETURNS int
+AS $CODE$
+DECLARE
+    strong_counter int := 0;
+    current int := 0;
+BEGIN
+
+    FOR i IN 1 .. array_length( nums, 1 ) - 1 LOOP
+        FOR j in ( i + 1 ) .. array_length( nums, 1 ) LOOP
+        	SELECT min( x )
+    		INTO current
+    		FROM unnest( array[ nums[ i ], nums[ j ] ] ) x;
+
+        	IF current > abs( nums[ i ] - nums[ j ] ) AND nums[ i ] <> nums[ j ] THEN
+    			strong_counter := strong_counter + 1;
+    	    END IF;
+        END LOOP;
+    END LOOP;
+
+    RETURN strong_counter;
+
+END
+$CODE$
+LANGUAGE plpgsql;
+
+
diff --git a/challenge-277/luca-ferrari/python/ch-1.py b/challenge-277/luca-ferrari/python/ch-1.py
new file mode 100644
index 0000000000..2634d9c077
--- /dev/null
+++ b/challenge-277/luca-ferrari/python/ch-1.py
@@ -0,0 +1,41 @@
+import sys
+
+# task implementation
+# the return value will be printed
+def task_1( args ):
+    words1 = []
+    words2 = []
+    first  = True
+    for w in args:
+        if w == '|':
+            first = False
+        if first:
+            words1.append( w )
+        else:
+            words2.append( w )
+
+    single1 = []
+    single2 = []
+    for w in words1:
+        if len( list( filter( lambda x: x == w, words1 ) ) ) == 1:
+            if not w in single1:
+                single1.append( w )
+
+    for w in words2:
+        if len( list( filter( lambda x: x == w, words2 ) ) ) == 1:
+            if not w in single2:
+                single2.append( w )
+
+    counting = 0
+    for w in single1:
+        if w in single2:
+            counting += 1
+
+    return counting
+
+
+# invoke the main without the command itself
+if __name__ == '__main__':
+    print( task_1( sys.argv[ 1: ] ) )
+
+
diff --git a/challenge-277/luca-ferrari/python/ch-2.py b/challenge-277/luca-ferrari/python/ch-2.py
new file mode 100644
index 0000000000..1b420ab4b7
--- /dev/null
+++ b/challenge-277/luca-ferrari/python/ch-2.py
@@ -0,0 +1,21 @@
+import sys
+
+# task implementation
+# the return value will be printed
+def task_2( args ):
+    nums = list( map( int, args ) )
+
+    strong = []
+
+    for i in range( 0, len( nums ) - 1 ):
+        for j in range( i + 1, len( nums ) ):
+            if nums[ i ] != nums[ j ] and abs( nums[ i ] - nums[ j ] ) < min( nums[ i ], nums[ j ] ):
+               strong.append( str( nums[ i ] ) + "<->" + str( nums[ j ] ) )
+
+    return len( strong )
+
+
+# invoke the main without the command itself
+if __name__ == '__main__':
+    print( task_2( sys.argv[ 1: ] ) )
+
diff --git a/challenge-277/luca-ferrari/raku/ch-1.raku b/challenge-277/luca-ferrari/raku/ch-1.raku
new file mode 100644
index 0000000000..556e0a28bc
--- /dev/null
+++ b/challenge-277/luca-ferrari/raku/ch-1.raku
@@ -0,0 +1,12 @@
+sub MAIN( :@left, :@right ) {
+    my %left-bag  = Bag.new( @left );
+    my %right-bag = Bag.new( @right );
+    my @matches;
+    my @single-left  = %left-bag.kv.grep( -> $k, $v { $v == 1 } ).map( *[ 0 ] );
+    my @single-right = %right-bag.kv.grep( -> $k, $v { $v == 1 } ).map( *[ 0 ] );
+    for @single-left -> $left {
+    	@matches.push( $left ) if ( @single-right.grep( * ~~ $left ) );
+    }
+
+    @matches.elems.say;
+}
diff --git a/challenge-277/luca-ferrari/raku/ch-2.raku b/challenge-277/luca-ferrari/raku/ch-2.raku
new file mode 100644
index 0000000000..14c303a342
--- /dev/null
+++ b/challenge-277/luca-ferrari/raku/ch-2.raku
@@ -0,0 +1,11 @@
+sub MAIN( *@nums where { @nums.grep( * ~~ Int ).elems == @nums.elems } ) {
+    #     A pair of integers x and y is called strong pair if it satisfies: 0 < |x - y| < min(x, y).
+    my @strong;
+    for 0 ..^ @nums.elems - 1 -> $i {
+    	for $i ^..^ @nums.elems -> $j {
+        @strong.push: [ @nums[ $i ], @nums[ $j ] ] if ( 0 < abs( @nums[ $i ] - @nums[ $j ] )  < min( @nums[ $i ], @nums[ $j ] ) );
+    	}
+    }
+
+    @strong.elems.say;
+}
diff --git a/challenge-280/eric-cheung/python/ch-1.py b/challenge-280/eric-cheung/python/ch-1.py
new file mode 100755
index 0000000000..df33741859
--- /dev/null
+++ b/challenge-280/eric-cheung/python/ch-1.py
@@ -0,0 +1,19 @@
+

+## Ref.

+## https://leetcode.com/problems/first-letter-to-appear-twice/description/

+## https://medium.com/@ac.shreedhar/2351-first-letter-to-appear-twice-in-java-970f99e3f625

+## https://algo.monster/liteproblems/2351

+

+def GetFirstAppearTwice (strFunc):

+    arrResult = [strFunc[0]]

+    for nIndx in range(1, len(strFunc)):

+        if strFunc[nIndx] in arrResult:

+            return strFunc[nIndx]

+        arrResult.append(strFunc[nIndx])

+    return ""

+

+## strInput = "acbddbca"  ## Example 1

+## strInput = "abccd"  ## Example 2

+strInput = "abcdabbb"  ## Example 3

+

+print (GetFirstAppearTwice (strInput))

diff --git a/challenge-280/eric-cheung/python/ch-2.py b/challenge-280/eric-cheung/python/ch-2.py
new file mode 100755
index 0000000000..d7bbc31000
--- /dev/null
+++ b/challenge-280/eric-cheung/python/ch-2.py
@@ -0,0 +1,14 @@
+

+## Ref.

+## https://leetcode.ca/2022-07-26-2315-Count-Asterisks/

+

+## strInput = "p|*e*rl|w**e|*ekly|"  ## Example 1

+## strInput = "perl"  ## Example 2

+strInput = "th|ewe|e**|k|l***ych|alleng|e"  ## Example 3

+

+if strInput.count("|") < 2:

+    print (strInput.count("*"))

+else:

+    arrSplit = strInput.split("|")

+    strResult = "".join([arrSplit[nIndx] for nIndx in range(len(arrSplit)) if nIndx % 2 == 0])

+    print (strResult.count("*"))

diff --git a/stats/pwc-challenge-279.json b/stats/pwc-challenge-279.json
new file mode 100644
index 0000000000..5d224cade5
--- /dev/null
+++ b/stats/pwc-challenge-279.json
@@ -0,0 +1,627 @@
+{
+   "xAxis" : {
+      "type" : "category"
+   },
+   "plotOptions" : {
+      "series" : {
+         "borderWidth" : 0,
+         "dataLabels" : {
+            "format" : "{point.y}",
+            "enabled" : 1
+         }
+      }
+   },
+   "subtitle" : {
+      "text" : "[Champions: 33] Last updated at 2024-07-29 10:44:57 GMT"
+   },
+   "legend" : {
+      "enabled" : 0
+   },
+   "chart" : {
+      "type" : "column"
+   },
+   "series" : [
+      {
+         "name" : "The Weekly Challenge - 279",
+         "data" : [
+            {
+               "drilldown" : "Ali Moradi",
+               "y" : 5,
+               "name" : "Ali Moradi"
+            },
+            {
+               "name" : "Andrew Schneider",
+               "y" : 3,
+               "drilldown" : "Andrew Schneider"
+            },
+            {
+               "y" : 2,
+               "name" : "Andrezgz",
+               "drilldown" : "Andrezgz"
+            },
+            {
+               "y" : 3,
+               "name" : "Arne Sommer",
+               "drilldown" : "Arne Sommer"
+            },
+            {
+               "y" : 4,
+               "name" : "Athanasius",
+               "drilldown" : "Athanasius"
+            },
+            {
+               "y" : 2,
+               "name" : "BarrOff",
+               "drilldown" : "BarrOff"
+            },
+            {
+               "drilldown" : "Bob Lied",
+               "y" : 2,
+               "name" : "Bob Lied"
+            },
+            {
+               "drilldown" : "Bruce Gray",
+               "y" : 2,
+               "name" : "Bruce Gray"
+            },
+            {
+               "drilldown" : "David Ferrone",
+               "y" : 2,
+               "name" : "David Ferrone"
+            },
+            {
+               "y" : 2,
+               "name" : "E. Choroba",
+               "drilldown" : "E. Choroba"
+            },
+            {
+               "name" : "Feng Chang",
+               "y" : 2,
+               "drilldown" : "Feng Chang"
+            },
+            {
+               "y" : 5,
+               "name" : "Jaldhar H. Vyas",
+               "drilldown" : "Jaldhar H. Vyas"
+            },
+            {
+               "drilldown" : "Jan Krnavek",
+               "y" : 2,
+               "name" : "Jan Krnavek"
+            },
+            {
+               "y" : 3,
+               "name" : "Jorg Sommrey",
+               "drilldown" : "Jorg Sommrey"
+            },
+            {
+               "y" : 2,
+               "name" : "Kjetil Skotheim",
+               "drilldown" : "Kjetil Skotheim"
+            },
+            {
+               "y" : 6,
+               "name" : "Laurent Rosenfeld",
+               "drilldown" : "Laurent Rosenfeld"
+            },
+            {
+               "drilldown" : "Mark Anderson",
+               "y" : 2,
+               "name" : "Mark Anderson"
+            },
+            {
+               "name" : "Matthew Neleigh",
+               "y" : 2,
+               "drilldown" : "Matthew Neleigh"
+            },
+            {
+               "drilldown" : "Matthias Muth",
+               "name" : "Matthias Muth",
+               "y" : 3
+            },
+            {
+               "drilldown" : "Nelo Tovar",
+               "name" : "Nelo Tovar",
+               "y" : 2
+            },
+            {
+               "y" : 2,
+               "name" : "Niels van Dijke",
+               "drilldown" : "Niels van Dijke"
+            },
+            {
+               "name" : "Packy Anderson",
+               "y" : 5,
+               "drilldown" : "Packy Anderson"
+            },
+            {
+               "drilldown" : "Peter Campbell Smith",
+               "name" : "Peter Campbell Smith",
+               "y" : 3
+            },
+            {
+               "drilldown" : "Peter Meszaros",
+               "y" : 2,
+               "name" : "Peter Meszaros"
+            },
+            {
+               "name" : "Reinier Maliepaard",
+               "y" : 3,
+               "drilldown" : "Reinier Maliepaard"
+            },
+            {
+               "drilldown" : "Robbie Hatley",
+               "y" : 3,
+               "name" : "Robbie Hatley"
+            },
+            {
+               "drilldown" : "Robert Ransbottom",
+               "name" : "Robert Ransbottom",
+               "y" : 2
+            },
+            {
+               "name" : "Roger Bell_West",
+               "y" : 5,
+               "drilldown" : "Roger Bell_West"
+            },
+            {
+               "drilldown" : "Santiago Leyva",
+               "y" : 2,
+               "name" : "Santiago Leyva"
+            },
+            {
+               "y" : 4,
+               "name" : "Thomas Kohler",
+               "drilldown" : "Thomas Kohler"
+            },
+            {
+               "drilldown" : "Ulrich Rieke",
+               "name" : "Ulrich Rieke",
+               "y" : 4
+            },
+            {
+               "name" : "W. Luis Mochan",
+               "y" : 3,
+               "drilldown" : "W. Luis Mochan"
+            },
+            {
+               "drilldown" : "Wanderdoc",
+               "name" : "Wanderdoc",
+               "y" : 2
+            }
+         ],
+         "colorByPoint" : 1
+      }
+   ],
+   "title" : {
+      "text" : "The Weekly Challenge - 279"
+   },
+   "yAxis" : {
+      "title" : {
+         "text" : "Total Solutions"
+      }
+   },
+   "drilldown" : {
+      "series" : [
+         {
+            "name" : "Ali Moradi",
+            "id" : "Ali Moradi",
+            "data" : [
+               [
+                  "Perl",
+                  2
+               ],
+               [
+                  "Raku",
+                  2
+               ],
+               [
+                  "Blog",
+                  1
+               ]
+            ]
+         },
+         {
+            "name" : "Andrew Schneider",
+            "id" : "Andrew Schneider",
+            "data" : [
+               [
+                  "Perl",
+                  2
+               ],
+               [
+                  "Blog",
+                  1
+               ]
+            ]
+         },
+         {
+            "data" : [
+               [
+                  "Perl",
+                  2
+               ]
+            ],
+            "id" : "Andrezgz",
+            "name" : "Andrezgz"
+         },
+         {
+            "id" : "Arne Sommer",
+            "data" : [
+               [
+                  "Raku",
+                  2
+               ],
+               [
+                  "Blog",
+                  1
+               ]
+            ],
+            "name" : "Arne Sommer"
+         },
+         {
+            "name" : "Athanasius",
+            "data" : [
+               [
+                  "Perl",
+                  2
+               ],
+               [
+                  "Raku",
+                  2
+               ]
+            ],
+            "id" : "Athanasius"
+         },
+         {
+            "name" : "BarrOff",
+            "id" : "BarrOff",
+            "data" : [
+               [
+                  "Raku",
+                  2
+               ]
+            ]
+         },
+         {
+            "name" : "Bob Lied",
+            "id" : "Bob Lied",
+            "data" : [
+               [
+                  "Perl",
+                  2
+               ]
+            ]
+         },
+         {
+            "data" : [
+               [
+                  "Raku",
+                  2
+               ]
+            ],
+            "id" : "Bruce Gray",
+            "name" : "Bruce Gray"
+         },
+         {
+            "data" : [
+               [
+                  "Perl",
+                  2
+               ]
+            ],
+            "id" : "David Ferrone",
+            "name" : "David Ferrone"
+         },
+         {
+            "name" : "E. Choroba",
+            "id" : "E. Choroba",
+            "data" : [
+               [
+                  "Perl",
+                  2
+               ]
+            ]
+         },
+         {
+            "name" : "Feng Chang",
+            "data" : [
+               [
+                  "Raku",
+                  2
+               ]
+            ],
+            "id" : "Feng Chang"
+         },
+         {
+            "name" : "Jaldhar H. Vyas",
+            "id" : "Jaldhar H. Vyas",
+            "data" : [
+               [
+                  "Perl",
+                  2
+               ],
+               [
+                  "Raku",
+                  2
+               ],
+               [
+                  "Blog",
+                  1
+               ]
+            ]
+         },
+         {
+            "id" : "Jan Krnavek",
+            "data" : [
+               [
+                  "Raku",
+                  2
+               ]
+            ],
+            "name" : "Jan Krnavek"
+         },
+         {
+            "name" : "Jorg Sommrey",
+            "id" : "Jorg Sommrey",
+            "data" : [
+               [
+                  "Perl",
+                  2
+               ],
+               [
+                  "Blog",
+                  1
+               ]
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