Valid Parentheses

EasyStringsMonotonic Stack

Solve this the way you would in the interview: out loud, on a timer, with an AI interviewer asking follow-ups while you code. You get a scored report at the end.

Practice this as a mock interviewFree to start, no account needed

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.

Examples

Input: s = "()"
Output: true
Input: s = "()[]{}"
Output: true
Input: s = "(]"
Output: false
Input: s = "([)]"
Output: false
Input: s = "{[]}"
Output: true

Constraints

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

What the interviewer grades

A correct solution is one of five scores. The report also grades problem understanding (did you clarify inputs and edge cases before coding), problem solving, communication while you work, code quality, and testing. See a sample report, or read up on the pattern in the lessons.

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