Day7.md

📅 Day 7 – Reflection

🔥 Theme: Real-World Patterns with Data & Code

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✅ Task 1: DSA – Top K Frequent Elements & Group Anagrams

Problems:

1. LeetCode 347: Top K Frequent Elements
2. LeetCode 49: Group Anagrams

What I did:
✔ Practiced using HashMap + PriorityQueue
✔ Solved problem using min-heap (top K frequent)
✔ Used sorted string as key for grouping anagrams
✔ Wrote both problems independently in VSCode
✔ Understood key concepts: Map.Entry, offer, poll, and entrySet

What I learned:

• Frequency maps
• Heap usage in sorting/top-k problems
• Hashing technique for grouping
• Clean and reusable logic with Java collections

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✅ Task 2: Core CS – TCP vs UDP + 3-Way Handshake

Topics Covered:

• TCP Reliability → 3-Way Handshake, sequence/acknowledgment
• UDP Characteristics → connectionless, low overhead-(additional resources needed to run tasks)
• Real-world apps: WhatsApp voice (UDP), YouTube stream (TCP)

Reflection:
✔ Visualized how handshake works
✔ Learned real difference in protocols
✔ Mapped protocols to actual use cases for interviews

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✅ Task 3: Python – Extracting Nested JSON Fields

What I did:

• Extracted customer id, name, and latest transaction amount
• Wrote clean function for one customer
• Enhanced to multiple customers using loop
• Printed output in table format

Reflection:
✔ Confident in parsing nested JSON
✔ Better understanding of dictionary traversal
✔ Practiced list of tuples and formatting output

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✅ Task 4: SQL – Window Functions

Completed Queries:

• Running total of sales using SUM() OVER(...)
• Rank of each sale using RANK() OVER(...)

What I learned:

• Window functions for analytic use-cases
• SQL power in breaking down complex logic simply

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Summary

✅ DSA: HashMap + Heap, Grouping with Key Pattern
✅ CS Concept: TCP/UDP + Handshake
✅ Python: JSON Parsing & Formatting
✅ SQL: Window Function – Running Total, Rank

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