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
C++ 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
bool balancedDelimiters(std::string text) {
}Worked examples
| Call | Result |
|---|---|
balancedDelimiters(std::string("()")) | true |
balancedDelimiters(std::string("([])")) | true |
balancedDelimiters(std::string("(]")) | false |
balancedDelimiters(std::string("[(])")) | false |
Hint
Push each opener, and when a closer arrives the top of the stack must be its matching opener.
Reference solution in C++
bool balancedDelimiters(std::string text) {
std::vector<char> expect;
for (char ch : text) {
if (ch == '(') expect.push_back(')');
else if (ch == '[') expect.push_back(']');
else if (ch == '{') expect.push_back('}');
else if (ch == ')' || ch == ']' || ch == '}') {
if (expect.empty() || expect.back() != ch) return false;
expect.pop_back();
}
}
return expect.empty();
}