Balanced brackets: Difference between revisions

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 =={{header|Batch File}}==
-Uses a Markov algorithm/code <code>"[]" -> null</code> to check if brackets are balanced.
+Uses the rewrite rule <code>"[]" -> null</code> to check if brackets are balanced.
-<lang dos>:: Balanced Brackets Task from Rosetta Code Wiki
+<lang dos>:: Balanced Brackets Task from Rosetta Code
 :: Batch File Implementation
@@ Line 1,154: / Line 1,154: @@
 setlocal enabledelayedexpansion
+set "num_pairs=10"
-::The Main Thing...
-set numofpairs=10
+set "num_strings=10"
-set howmanystrings=10
+:: the main thing
-cls
-for /l %%. in (1,1,%howmanystrings%) do (
+for /l %%s in (1, 1, %num_strings%) do (
-	call :generate
+    call :generate
-	call :checkforbalance
+    call :check
 )
-echo.&pause&exit /b
+echo(
+pause
-::/The Main Thing.
+exit /b 0
-::Generate strings of brackets...
+:: generate strings of brackets
 :generate
+set "string="
-	set i=0&set j=%numofpairs%&set samp=
+rem put %num_pairs% number of "[" in string
-	set /a toss=%random%%%2
+for /l %%c in (1, 1, %num_pairs%) do set "string=!string!["
-	set put1=[&set put2=]
+rem put %num_pairs% number of "]" in random spots of string
-	if %toss%==1 (set put1=]&set put2=[)
+set "ctr=%num_pairs%"
-	for /l %%x in (1,1,%numofpairs%) do (
+for /l %%c in (1, 1, %num_pairs%) do (
-		set samp=!samp!%put1%
+    set /a "rnd=!random! %% (!ctr! + 1)"
-	)
+    for %%x in (!rnd!) do (
-	:add
+        set "left=!string:~0,%%x!"
-	if not %i%==%numofpairs% (
+        set "right=!string:~%%x!"
-		set /a rnd=%random%%%%j%+1
+    )
-		set /a oppos=%j%-!rnd!
+    set "string=!left!]!right!"
-		::A new trick for substitution of delayed variables...
+    set /a "ctr+=1"
-		for /f "tokens=1-2" %%A in ("!rnd! !oppos!") do (
+)
-			set str1=!samp:~-%%A!
-			set str2=!samp:~0,%%B!
-		)
-		set samp=!str2!%put2%!str1!
-		set /a "j+=1","i+=1"
-		goto :add
-	)
 goto :EOF
-::/Generate strings of brackets.
-::Check for Balance...
+:: check for balance
+:check
-::Uses Markov Algorithm.
+set "new=%string%"
-:checkforbalance
-set "changes=!samp!"
 :check_loop
-if "!changes!"=="" goto itsbal
+if "%new%" equ "" (
+    echo(
-if "!input!"=="!changes!" goto notbal
+    echo(%string% is Balanced.
+    goto :EOF
-set input=!changes!
+) else if "%old%" equ "%new%" (   %== unchangeable already? ==%
-set "changes=!input:[]=!"
+    echo(
-goto check_loop
+    echo(%string% is NOT Balanced.
+    goto :EOF
-:itsbal
+)
-echo.
+rem apply rewrite rule "[]" -> null
-echo %samp% is Balanced.
+set "old=%new%"
-goto :EOF
+set "new=%old:[]=%"
-:notbal
+goto check_loop</lang>
-echo.
-echo %samp% is NOT Balanced.
-goto :EOF
-::/Check for Balance.</lang>
 {{out}}
+<pre>[][][[[[]]][]]]][[][ is NOT Balanced.
-<pre>
-[][][[]][][]]][][][[ is NOT Balanced.
-[[[[[]][[]][]][][]]] is Balanced.
+][[]][][][[]]][[[[]] is NOT Balanced.
-[[[[[]]]]][][][]][][ is NOT Balanced.
+[[[][]][][]][[][][]] is Balanced.
-][[[[[[[]]][]]][][]] is NOT Balanced.
+][[[[[]]][][][][][]] is NOT Balanced.
-[][[[[]]]][[[[]]]][] is Balanced.
+]][][[][]]]][]][[[[[ is NOT Balanced.
-[[[][[[]][][]]]][][] is Balanced.
+[[[][[][][[]]]][][]] is Balanced.
-[[][[]][[]]]]][][[[] is NOT Balanced.
+][]]][[]][[][[][[]][ is NOT Balanced.
-[][][]][][]]][][][[[ is NOT Balanced.
+[[[][[][]][[[]]][]]] is Balanced.
-[[]][][][[][[[]]]][] is Balanced.
+]][]]][[[][]][[][[[] is NOT Balanced.
-[[[[[][[][[]]]]][]]] is Balanced.
+][[]][][[]][][]][[][ is NOT Balanced.
 Press any key to continue . . .</pre>