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This is a easy difficulty Coding & Algorithms question, commonly asked during Technical Screen rounds at Boston.

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This question is commonly asked for Data Scientist candidates at Boston during technical interviews.

Implement palindrome check and valid parentheses

Q: Implement palindrome check and valid parentheses

This question evaluates string-processing skills, algorithmic reasoning, and attention to edge cases by asking for a palindrome detector and a parentheses-sequence validator.

You have 20–25 minutes per problem. Implement the following two functions and be prepared to explain your approach and time/space complexity.

Problem 1 — Palindrome Check

Write a function that determines whether a given string is a palindrome.

A string is a palindrome if it reads the same forward and backward.
Compare characters exactly as they appear (no case folding and no ignoring punctuation/whitespace unless you explicitly state and implement it).

Function signature (example):

bool is_palindrome(s: str)

Input:

s : a string (may be empty)

Output:

true if s is a palindrome, otherwise false

Examples:

"abba" -> true
"abc" -> false
"" -> true

Problem 2 — Valid Parentheses Sequence

Write a function that checks whether a string containing only parentheses characters is valid.

A string is valid if:

Every opening bracket has a corresponding closing bracket of the same type.
Brackets close in the correct order.

Assume the allowed bracket types are: (), [], {}.

Function signature (example):

bool is_valid_parentheses(s: str)

Input:

s : a string consisting only of characters in ()[]{} (may be empty)

Output:

true if s is valid, otherwise false

Examples:

"()" -> true
"([]){}" -> true
"(]" -> false
"([)]" -> false
"" -> true

Documentation requirement

For each function, include a docstring with:

Description
Inputs/Outputs
Callouts (assumptions, edge cases, complexity)

You have 20–25 minutes per problem. Implement the following two functions and be prepared to explain your approach and time/space complexity.

Problem 1 — Palindrome Check

Write a function that determines whether a given string is a palindrome.

A string is a palindrome if it reads the same forward and backward.
Compare characters exactly as they appear (no case folding and no ignoring punctuation/whitespace unless you explicitly state and implement it).

Function signature (example):

bool is_palindrome(s: str)

Input:

s : a string (may be empty)

Output:

true if s is a palindrome, otherwise false

Examples:

"abba" -> true
"abc" -> false
"" -> true

Problem 2 — Valid Parentheses Sequence

Write a function that checks whether a string containing only parentheses characters is valid.

A string is valid if:

Every opening bracket has a corresponding closing bracket of the same type.
Brackets close in the correct order.

Assume the allowed bracket types are: (), [], {}.

Function signature (example):

bool is_valid_parentheses(s: str)

Input:

s : a string consisting only of characters in ()[]{} (may be empty)

Output:

true if s is valid, otherwise false

Examples:

"()" -> true
"([]){}" -> true
"(]" -> false
"([)]" -> false
"" -> true

Documentation requirement

For each function, include a docstring with:

Description
Inputs/Outputs
Callouts (assumptions, edge cases, complexity)

Implement palindrome check and valid parentheses

Quick Overview

Problem 1 — Palindrome Check

Problem 2 — Valid Parentheses Sequence

Documentation requirement

Submit Your Answer to Earn 20XP

Implement palindrome check and valid parentheses

Quick Overview

Problem 1 — Palindrome Check

Problem 2 — Valid Parentheses Sequence

Documentation requirement

Submit Your Answer to Earn 20XP