Data commit

Task/Run-length-encoding/SQL/run-length-encoding-1.sql

@@ -0,0 +1,47 @@
+-- variable table
+drop table if exists var;
+create temp table var (	value varchar(1000) );
+insert into var(value) select 'WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW';
+
+-- select
+with recursive
+ints(num) as
+(
+	select 1
+	union all
+	select num+1
+	from ints
+	where num+1 <= length((select value from var))
+)
+,
+chars(num,chr,nextChr,isGroupEnd) as
+(
+	select tmp.*, case when tmp.nextChr <> tmp.chr then 1 else 0 end groupEnds
+	from (
+	select num,
+		   substring((select value from var), num, 1) chr,
+		   (select substring((select value from var), num+1, 1)) nextChr
+	from ints
+	) tmp
+)
+select (select value from var) plain_text, (
+	select string_agg(concat(cast(maxNoWithinGroup as varchar(10)) , chr), '' order by num)
+	from (
+		select *, max(noWithinGroup) over (partition by chr, groupNo) maxNoWithinGroup
+		from (
+			select	num,
+					chr,
+					groupNo,
+					row_number() over( partition by chr, groupNo order by num) noWithinGroup
+			from (
+			select *, (select count(*)
+					   from chars chars2
+					   where chars2.isGroupEnd = 1 and
+					   chars2.chr = chars.chr and
+					   chars2.num < chars.num) groupNo
+			from chars
+			) tmp
+		) sub
+	) final
+	where noWithinGroup = 1
+	) Rle_Compressed

Task/Run-length-encoding/SQL/run-length-encoding-2.sql

@@ -0,0 +1,62 @@
+-- variable table
+DROP TABLE IF EXISTS var;
+CREATE temp TABLE var (	VALUE VARCHAR(1000) );
+INSERT INTO var(VALUE) SELECT '1A2B3C4D5E6F';
+
+-- select
+WITH recursive
+ints(num) AS
+(
+	SELECT 1
+	UNION ALL
+	SELECT num+1
+	FROM ints
+	WHERE num+1 <= LENGTH((SELECT VALUE FROM var))
+)
+,
+chars(num,chr,nextChr) AS
+(
+	SELECT tmp.*
+	FROM (
+	SELECT num,
+		SUBSTRING((SELECT VALUE FROM var), num, 1) chr,
+		(SELECT SUBSTRING((SELECT VALUE FROM var), num+1, 1)) nextChr
+	FROM ints
+	) tmp
+)
+,
+charsWithGroup(num,chr,nextChr,group_no) AS
+(
+	SELECT *,(SELECT COUNT(*)
+		FROM chars chars2
+		WHERE chars2.chr !~ '[0-9]' AND
+		chars2.num < chars.num) group_No
+	FROM chars
+)
+,
+charsWithGroupAndLetter(num,chr,nextChr,group_no,group_letter) AS
+(
+	SELECT *,(SELECT chr
+		FROM charsWithGroup g2
+		where g2.group_no = charsWithGroup.group_no
+		ORDER BY num DESC
+		LIMIT 1)
+	FROM charsWithGroup
+)
+,
+lettersWithCount(group_no,amount,group_letter) AS
+(
+	SELECT group_no, string_agg(chr, '' ORDER BY num), group_letter
+	FROM charsWithGroupAndLetter
+	WHERE chr ~ '[0-9]'
+	GROUP BY group_no, group_letter
+)
+,
+lettersReplicated(group_no,amount,group_letter, replicated_Letter) AS
+(
+	SELECT *, rpad(group_letter, cast(amount as int), group_letter)
+	FROM lettersWithCount
+)
+select (SELECT value FROM var) rle_encoded,
+	string_agg(replicated_Letter, '' ORDER BY group_no) decoded_string
+FROM lettersReplicated