Balanced brackets: Difference between revisions

=={{header|FreeBASIC}}==

<lang freebasic>' FB 1.05.0 Win64

Function isBalanced(s As String) As Boolean

If s = "" Then Return True

Dim countLeft As Integer = 0 '' counts number of left brackets so far unmatched

Dim c As String

For i As Integer = 1 To Len(s)

c = Mid(s, i, 1)

If c = "[" Then

countLeft += 1

ElseIf countLeft > 0 Then

countLeft -= 1

Else

Return False

End If

Next

Return countLeft = 0

End Function

' checking examples in task description

Dim brackets(1 To 7) As String = {"", "[]", "][", "[][]", "][][", "[[][]]", "[]][[]"}

For i As Integer = 1 To 7

Print IIf(brackets(i) <> "", brackets(i), "(empty)"); Tab(10); IIf(isBalanced(brackets(i)), "OK", "NOT OK")

Next

' checking 7 random strings of brackets of length 8 say

Randomize

Dim r As Integer '' 0 will signify "[" and 1 will signify "]"

Dim s As String

For i As Integer = 1 To 7

s = Space(8)

For j As Integer = 1 To 8

r = Int(Rnd * 2)

If r = 0 Then

Mid(s, j) = "["

Else

Mid(s, j) = "]"

End If

Next j

Print s; Tab(10); IIf(isBalanced(s), "OK", "NOT OK")

Next i

Print

Print "Press any key to quit"

Sleep</lang>

Sample output (last 7 lines random) :

{{out}}

<pre>

(empty) OK

[] OK

][ NOT OK

[][] OK

][][ NOT OK

[[][]] OK

[]][[] NOT OK

][]][[[[ NOT OK

[]][][]] NOT OK

][][[[]] NOT OK

[[[[]]]] OK

[][[[[][ NOT OK

][[[]][] NOT OK

[][[[[][ NOT OK

</pre>