Review the AI

Balanced Brackets

An interview favourite, three AI answers. Label each solution.

Problem

balanced(s): s holds only ()[]. Return True if every bracket closes with the right kind in the right order: "([])" is fine, "([)]" is not.

Solution A

1def balanced(s):

2 pairs = {")": "(", "]": "["}

3 stack = []

4 for ch in s:

5 if ch in pairs:

6 if not stack or stack.pop() != pairs[ch]:

7 return False

8 else:

9 stack.append(ch)

10 return not stack

Solution B

1def balanced(s):

2 return s.count("(") == s.count(")") and s.count("[") == s.count("]")

Solution C

1def balanced(s):

2 while "()" in s or "[]" in s:

3 s = s.replace("()", "").replace("[]", "")

4 return s == ""