Balanced delimiters
A config linter walks a snippet and rejects it if the brackets, braces and parentheses do not nest cleanly.
- Only the characters ( ) [ ] { } matter; everything else is ignored.
- Every opener must have a matching closer of the same kind, in the right order.
- An empty snippet — or one with no brackets at all — is fine.
balancedDelimiters(text: string) → bool
Go needs a compiler and Drill does not host one yet, so this page is the reference rather than an exercise: the problem, worked examples, and the solution in full. To type it out, the same problem runs in Python.
Where you start
func balancedDelimiters(text string) bool {
}Worked examples
| Call | Result |
|---|---|
balancedDelimiters("()") | true |
balancedDelimiters("([])") | true |
balancedDelimiters("(]") | false |
balancedDelimiters("[(])") | false |
Hint
Push each opener, and when a closer arrives the top of the stack must be its matching opener.
Reference solution in Go
func balancedDelimiters(text string) bool {
expect := []byte{}
for i := 0; i < len(text); i++ {
ch := text[i]
if ch == '(' {
expect = append(expect, ')')
} else if ch == '[' {
expect = append(expect, ']')
} else if ch == '{' {
expect = append(expect, '}')
} else if ch == ')' || ch == ']' || ch == '}' {
if len(expect) == 0 || expect[len(expect)-1] != ch {
return false
}
expect = expect[:len(expect)-1]
}
}
return len(expect) == 0
}