Valid Parentheses
EasyTime 1000 msMemory 128 MB
You are given a string s containing only the characters (, ), {, }, [ and ].
Decide whether the brackets are balanced. A string is balanced if every opening bracket closes with the matching kind, in the right order.
Input format
A single line: the string s (1 ≤ |s| ≤ 10^5). The string contains only the six bracket characters above and no whitespace.
Output format
A single line: true if s is balanced, false otherwise. (Lowercase, exactly as shown.)
Constraints
- The empty string is not a valid input (the length is at least 1).
- A stack of expected closers is the standard
O(n)solution.
Example 1
Input
()
Output
true
Explanation: A single pair.
Example 2
Input
()[]{}Output
true
Explanation: Three balanced pairs in sequence.
Example 3
Input
(]
Output
false
Explanation: The ( expects a ) to close it, not a ].
Example 4
Input
([)]
Output
false
Explanation: Interleaved, not nested — the [ must close before the ( does.
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Input
()
Expected output
true
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