Question 1

What is the fast and slow pointer technique?

Accepted Answer

**Target Audience:** Beginners preparing for coding interviews — no prior algorithms knowledge assumed
**Difficulty:** Easy
**Language:** Python 3

> **How to read this doc:** Every idea is explained in plain language first, then tagged with `📌 Interview term:` so you also learn the exact word an interviewer expects. All code is Python, and every output block in the **Verified** section was copied from a real run of the examples on this page.

## 1. Why This Even Matters — A Story First

A tort

Question 2

What is a trie and when is it useful?

Accepted Answer

**Target Audience:** Beginners preparing for coding interviews — you need loops, classes and the idea of a tree.  
**Difficulty:** Medium  
**Language:** Python 3

> **How to read this doc:** every idea is explained in plain words first. When a word appears that an interviewer will expect you to know, it is tagged `📌 Interview term:` with a one-line definition, and every tagged term is collected in the Quick Glossary at the end. Every program on this page was actually run, and the output you se

Question 3

How do you solve the word break problem?

Accepted Answer

**Target Audience:** Beginners preparing for coding interviews — you need loops, strings and hash sets; the DP is built up from scratch.  
**Difficulty:** Medium  
**Language:** Python 3

> **How to read this doc:** every idea is explained in plain words first. When a word appears that an interviewer will expect you to know, it is tagged `📌 Interview term:` with a one-line definition, and every tagged term is collected in the Quick Glossary at the end. Every program on this page was actually ru

Question 4

How do you detect a cycle in a linked list?

Accepted Answer

**Target Audience:** Beginners preparing for coding interviews — no prior algorithms knowledge assumed
**Difficulty:** Medium
**Language:** Python 3

> **How to read this doc:** Every idea is explained in plain language first, then tagged with `📌 Interview term:` so you also learn the exact word an interviewer expects. All code is Python, and every output block in the **Verified** section was copied from a real run of the examples on this page.

## 1. Why This Even Matters — A Story First

You

Question 5

Longest consecutive sequence in O(n) with hash set — why not sort?

Accepted Answer

**Target Audience:** Intermediate candidates — you should know arrays and what a hash set does; Big-O basics help.
**Difficulty:** Medium
**Language:** Python 3

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:` so you also learn the exact words an interviewer expects. Every output shown in the **Verified** section was produced by actually running the Python code with `python3 main.py`; nothing is quoted from memory.

## 1. Why This

DATA STRUCTURES & ALGORITHMSDECODED.

Easy

What is the fast and slow pointer technique?

Medium

What is a trie and when is it useful?

How do you solve the word break problem?

How do you detect a cycle in a linked list?

Longest consecutive sequence in O(n) with hash set — why not sort?