Summary
Check whether a string of brackets is balanced and properly nested using a stack.
Problem statement
Given a string containing characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: 1) Open brackets are closed by the same type of brackets. 2) Open brackets are closed in the correct order. 3) An empty string is considered valid. Use a stack to verify the correctness efficiently.
Task
Implement a function that returns True if the input string contains valid matching pairs of parentheses, brackets, and braces; otherwise False.
Examples
Simple balanced
Input
validate_parentheses('([{}])')
Output
True
Explanation
All opening brackets are matched in the correct order with corresponding closing brackets.
Input format
A single string s containing only the characters '(', ')', '{', '}', '[' and ']'. Example: '([{}])'
Output format
Return True if s is valid, otherwise return False.
Constraints
0 <= len(s) <= 10^4; only the six bracket characters appear.
Samples
Sample input 0
validate_parentheses('()')
Sample output 0
True
Explanation 0
A simple matching pair is valid.
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