Section 1Understand Problem
Section 01
Understand the problem
Restate the problem precisely. Interviewers reward candidates who pause, define the contract, and name the guarantees before coding.
Problem statement
Given a string `s` containing just the characters `'('`, `')'`, `'{'`, `'}'`, `'['` and `']'`, determine if the input string is valid. An input string is valid if open brackets are closed by the same type of brackets, in the correct order, and every close bracket has a matching open bracket of the same type.
Example
s = "()" → true
Constraints
1 ≤ s.length ≤ 10⁴ · s consists of parentheses only '()[]{}'
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