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Valid Parentheses | CodeTutor

Valid Parentheses

Easy

Strings Stack Monotonic Stack

Problem

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

An input string is valid if:

Open brackets must be closed by the same type of brackets.
Open brackets must be closed in the correct order.
Every close bracket has a corresponding open bracket of the same type.

Constraints

1 <= s.length <= 10^4
s consists of parentheses only '()[]{}'

Examples

Input: s = "()"

Output: true

Single pair of matching parentheses.

Input: s = "()[]{}"

Output: true

Three separate valid pairs.

Input: s = "(]"

Output: false

Mismatched bracket types.

Input: s = "([)]"

Output: false

Incorrect nesting order — the inner bracket must close before the outer one.

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