How do I approach Coding & Algorithms interview questions?

Coding & Algorithms questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master coding & algorithms interviews.

What difficulty level is this interview question?

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

What role is this question designed for?

This question is commonly asked for Software Engineer candidates at TikTok during technical interviews.

Solve linked list, string filtering, and puzzle

Q: Solve linked list, string filtering, and puzzle

This multi-part question evaluates proficiency with linked-list pointer manipulation and constant-space linear-time algorithms, pattern-driven string transformation with attention to iteration semantics and edge-case handling, and combinatorial reasoning about constrained resource partitioning.

Coding & Algorithms (3 tasks)

1) Find the 5th node from the end (singly linked list)

You are given the head pointer of a singly linked list.

Return the value of the node that is the 5th from the end (i.e., counting from the tail: tail is 1st).
If the list has fewer than 5 nodes, specify a reasonable behavior (e.g., return null / throw an error).

Constraints: Aim for $O(n)$ time and $O(1)$ extra space.

2) Remove “camel-pattern” triplets from a string

Given a string s (ASCII letters only), remove every contiguous length-3 substring s[i..i+2] that matches the pattern:

s[i] == s[i+2] (exact same character), and
s[i] and s[i+1] have different letter cases (one uppercase, one lowercase).

After removals, the remaining parts are concatenated.

Example

Input: "AaADbDEeEbcvQv"
Output: "bc"

Clarify whether removals are single pass or repeated until no more matches; design your solution accordingly.

Constraints: $1 \le |s| \le 2\times 10^5$ .

3) Gold bar daily pay puzzle

A worker works 7 days and is paid one gold bar total. The bar can be broken into pieces with at most two breaks.

How can you pay the worker each day such that the daily payment is equal (i.e., each day receives exactly $\tfrac{1}{7}$ of the total bar value)?
You may exchange pieces back and forth each day (give/take pieces) as long as the net pay per day is correct.

Coding & Algorithms (3 tasks)

1) Find the 5th node from the end (singly linked list)

You are given the head pointer of a singly linked list.

Return the value of the node that is the 5th from the end (i.e., counting from the tail: tail is 1st).
If the list has fewer than 5 nodes, specify a reasonable behavior (e.g., return null / throw an error).

Constraints: Aim for $O(n)$ time and $O(1)$ extra space.

2) Remove “camel-pattern” triplets from a string

Given a string s (ASCII letters only), remove every contiguous length-3 substring s[i..i+2] that matches the pattern:

s[i] == s[i+2] (exact same character), and
s[i] and s[i+1] have different letter cases (one uppercase, one lowercase).

After removals, the remaining parts are concatenated.

Example

Input: "AaADbDEeEbcvQv"
Output: "bc"

Clarify whether removals are single pass or repeated until no more matches; design your solution accordingly.

Constraints: $1 \le |s| \le 2\times 10^5$ .

3) Gold bar daily pay puzzle

A worker works 7 days and is paid one gold bar total. The bar can be broken into pieces with at most two breaks.

How can you pay the worker each day such that the daily payment is equal (i.e., each day receives exactly $\tfrac{1}{7}$ of the total bar value)?
You may exchange pieces back and forth each day (give/take pieces) as long as the net pay per day is correct.

Solve linked list, string filtering, and puzzle

Quick Overview

Coding & Algorithms (3 tasks)

1) Find the 5th node from the end (singly linked list)

2) Remove “camel-pattern” triplets from a string

3) Gold bar daily pay puzzle

Comments (0)

Solve linked list, string filtering, and puzzle

Quick Overview

Coding & Algorithms (3 tasks)

1) Find the 5th node from the end (singly linked list)

2) Remove “camel-pattern” triplets from a string

3) Gold bar daily pay puzzle

Comments (0)