Balanced brackets: Difference between revisions

=={{header|REXX}}==

<lang rexx>

/*check for balanced brackets [] */

@.=0

yesno.0=left('',40) 'unbalanced'

yesno.1='balanced'

q='[][][][[]]' ; call checkBal q; say yesno.result q

q='[][][][[]]][' ; call checkBal q; say yesno.result q

q='[' ; call checkBal q; say yesno.result q

q=']' ; call checkBal q; say yesno.result q

q='[]' ; call checkBal q; say yesno.result q

q='][' ; call checkBal q; say yesno.result q

q='][][' ; call checkBal q; say yesno.result q

q='[[]]' ; call checkBal q; say yesno.result q

q='[[[[[[[]]]]]]]' ; call checkBal q; say yesno.result q

q='[[[[[]]]][]' ; call checkBal q; say yesno.result q

q='[][]' ; call checkBal q; say yesno.result q

q='[]][[]' ; call checkBal q; say yesno.result q

q=']]][[[[]' ; call checkBal q; say yesno.result q

do j=1 for 40

q=translate(rand(random(1,8)),'[]',01)

call checkBal q; if result=-1 then iterate

say yesno.result q

end

exit

pand:p=random(0,1);return p||\p

rand:pp=pand();pp=pand()pp;pp=copies(pp,arg(1));

i=random(2,length(pp))

pp=left(pp,i-1)substr(pp,i)

return pp

/*─────────────────────────────────────check for balanced brackets [] */

checkBal: procedure expose @.; arg y; nest=0

if @.y then return -1 /*already done this expression ? */

@.y=1 /*indicate expression processed. */

do j=1 for length(y)

_=substr(y,j,1)

if _=='[' then nest=nest+1

else do; nest=nest-1; if nest<0 then return 0; end

end

return nest==0

</lang>

<pre style="height:40ex;overflow:scroll">

Output (not repleatable due to the use of RANDOM:

balanced [][][][[]]

unbalanced [][][][[]]][

unbalanced [

unbalanced ]

balanced []

unbalanced ][

unbalanced ][][

balanced [[]]

balanced [[[[[[[]]]]]]]

unbalanced [[[[[]]]][]

balanced [][]

unbalanced []][[]

unbalanced ]]][[[[]

unbalanced ][[]][[]][[]][[]][[]

unbalanced []][[]][[]][[]][[]][

unbalanced []][

balanced [][][][][][][][][][][][][][][][]

unbalanced []][[]][[]][

balanced [][][][][][][][]

unbalanced ][][][][][][][][

unbalanced ][[]][[]][[]][[]][[]][[]

unbalanced []][[]][[]][[]][[]][[]][[]][[]][

unbalanced ][][][][][][][][][][

unbalanced ][][][][][][][][][][][][][][

unbalanced ][][][][][][][][][][][][][][][][

unbalanced ][[]][[]][[]][[]][[]][[]][[]

unbalanced []][[]][[]][[]][[]][[]][[]][

unbalanced ][][][][

unbalanced []][[]][

balanced [][][][][][][][][][][][]

unbalanced ][[]

unbalanced []][[]][[]][[]][[]][[]][

unbalanced ][][][][][][

balanced [][][][][][][][][][]

balanced [][][][][][][][][][][][][][]

balanced [][][][]

unbalanced ][[]][[]][[]][[]

unbalanced ][[]][[]][[]][[]][[]][[]][[]][[]

unbalanced ][][][][][][][][][][][][

</pre>