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  1. def check(input_string):
  2. 	stack = []
  3. 	brackets     = { '{': '}', '(': ')', '[': ']' }
  4. 	brackets_rev = {v: k for k, v in brackets.items()}
  5. 	for idx, ch in enumerate(input_string):
  6. 		if ch in brackets:
  7. 			stack.append(ch)
  8. 		elif ch in brackets_rev:
  9. 			if not stack:
  10. 				return False, 'Closing parenthesis without open one at {0}'.format(idx)
  11.  
  12. 			if stack.pop(-1) != brackets_rev[ch]:
  13. 				return False, 'Invalid bracket at idx {0}: "{1}" (expected "{2}")'.format(idx, ch, brackets_rev[ch])
  14.  
  15. 	if stack:
  16. 		return False, 'Unbalanced: {0}'.format(', '.join(stack))
  17. 	return True, None
  18.  
  19. print(check("()"))
  20. print(check("[{}]()"))
  21. print(check("({)[}]"))
Success #stdin #stdout 0.02s 5852KB
comments (?)
stdin 
Standard input is empty
stdout 
(True, None)
(True, None)
(False, 'Invalid bracket at idx 2: ")" (expected "(")')
https://ideone.com/jgZo1
language:
Python 3 (python  3.9.5)
created:
12 years ago
visibility:
secret

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