When to use LinkedHashMap vs HashMap? | Character Frequencies Problem

Описание: Coding Interview Question: Character Frequencies | Java LinkedHashMap Solution

Mastering the *Hash Map* pattern is one of the most effective ways to ace your technical interviews. In this video, we tackle the *Character Frequencies* problem from InterviewBit, perfect for building your foundation in data structures.

📝 What You’ll Learn:

*The Problem:* Given a string of lowercase characters, how do you find the frequency of each character in the exact order they first appear?
*The Data Structure:* Why a standard `HashMap` might fail you in Java and how the *LinkedHashMap* solves the ordering problem effortlessly.
*The Alternative Strategy:* Learn a "two-pass" approach using a regular map and a frequency reset trick—essential if you’re asked to solve this without specialized collections.
*Time & Space Complexity:* Understanding how to handle input strings up to 10^5 characters efficiently.

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0:00 - Introduction to Character Frequencies
0:51 - Problem Description & Constraints
1:21 - Example Walkthrough: Understanding "Order of Occurrence"
2:42 - Java Solution: Why LinkedHashMap is the "Perfect" Tool
3:39 - Python Behavior Note
5:17 - Bonus: How to solve it using a standard HashMap
7:14 - Outro & Next Steps