📚 PCT Coding Test Environment - December 2025

🎯 Overview

This folder contains 81 DSA coding questions from the December 2025 PCT Exams, organized as a complete coding test environment.

📁 Structure

All questions are organized by file number (1-9) with 9 questions each:

CodingTest/
├── File1_Q1 to Q9 (Array, Hashing, Stack, String, Matrix)
├── File2_Q1 to Q9 (Binary Search, Greedy, Two-Pointer, Linked List)
├── File3_Q1 to Q9 (Sorting, Search, Stack, String, BST)
├── File4_Q1 to Q9 (Queue, Matrix, Hashing, Stack)
├── File5_Q1 to Q9 (Linked List, Matrix, DP, Heap, Sliding Window)
├── File6_Q1 to Q9 (String, Sorting, Array, Stack)
├── File7_Q1 to Q9 (Array, Stack, Tree, Linked List)
├── File8_Q1 to Q9 (String, Queue, Matrix, Heap, Backtracking)
└── File9_Q1 to Q9 (Sorting, DP, Hashing, Two-Pointer, Linked List)

🚀 How to Use

Step 1: Choose a Question

Open any file (e.g., File1_Q1_FamilyPhotograph.java)

Step 2: Read the Problem

Each file contains:

• ✅ Problem statement
• ✅ Classification (Array, Stack, etc.)
• ✅ Test cases with expected outputs
• ✅ Algorithm hint
• ✅ Similar questions for more practice

Step 3: Implement Your Solution

Find the // YOUR CODE HERE sections and write your solution.

Step 4: Run and Test

cd CodingTest
javac File1_Q1_FamilyPhotograph.java
java File1_Q1_FamilyPhotograph

Step 5: Check Results

The program automatically validates with:

• ✓ PASSED - Your solution is correct
• ✗ FAILED - Review your implementation

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📋 Complete Question List

File 1 (Array, Hashing, Stack, String, Matrix)

#	Question	Topic
1	Family Photograph (Reverse in K-blocks)	Array
2	Airline Baggage Tracking (Unique IDs)	Hashing
3	Cleaning String (Remove Leading Zeros)	String
4	Tray Stack (Receive/Serve)	Stack
5	Prefix Calculator	Stack
6	Seat Reservation (2D Array)	Matrix
7	First Unique Character	Hashing
8	Reverse Words in String	String
9	Matrix Diagonals Sum	Matrix

File 2 (Binary Search, Greedy, Two-Pointer)

#	Question	Topic
1	Last Occurrence (Binary Search)	Binary Search
2	Maximize Sum (First + Last)	Greedy
3	Find Rotation Count	Binary Search
4	Total Search Time	Array
5	Audit Function (Find Mode)	Hashing
6	Move Zeroes	Two-Pointer
7	Merge Sorted Arrays	Two-Pointer
8	Find Peak Element	Binary Search
9	Reverse Linked List	Linked List

File 3 (Sorting, Search, Stack, BST)

#	Question	Topic
1	Insertion Sort Energy (Shifts × 4)	Sorting
2	Decreasing Search (Binary Search Desc)	Binary Search
3	Employee Search (ID/Name)	Search
4	Braces Balance (Bracket Matching)	Stack
5	String Compression (RLE)	String
6	Word Frequency	Hashing
7	Warehouse Inventory (Linked List)	Linked List
8	Odd-Even Linked List	Linked List
9	BST Operations	Tree

File 4 (Queue, Matrix, Hashing, Stack)

#	Question	Topic
1	Reverse Queue	Queue
2	Recursive Queue Reverse	Queue
3	Code Compiler Brackets	Stack
4	Search Matrix (Staircase)	Matrix
5	Unique Elements	Hashing
6	Heat Wave (Max Temp, Trends)	Array
7	Run-Length Encoding	String
8	Missing Number (1..N)	Math
9	Baseball Game	Stack

File 5 (Linked List, Matrix, DP, Heap)

#	Question	Topic
1	N-th Node from End	Linked List
2	Remove Duplicates (Sorted)	Linked List
3	Matrix Multiplication	Matrix
4	Max Profit (Stock)	DP/Greedy
5	K-th Smallest Element	Heap
6	Smallest Window Substring	Sliding Window
7	Counting Characters	Hashing
8	Fair Distribution (Candy)	Greedy
9	Caesar Cipher	String

File 6 (String, Sorting, Array, Stack)

#	Question	Topic
1	Palindrome Check	Two-Pointer
2	Reverse Queue using Stack	Stack/Queue
3	Placement Drive (Sort by CGPA)	Sorting
4	Second Highest	Array
5	Examination Marks (+4/-1)	Array
6	Height Report (Statistics)	Array
7	Matrix Row Sum	Matrix
8	Valid Parentheses	Stack
9	Baseball Game V2	Stack

File 7 (Array, Stack, Tree, Linked List)

#	Question	Topic
1	Even/Odd Count	Array
2	Negative Profit Days	Array
3	Sum of Digits	Math
4	Partial Stack Reversal	Stack
5	Ticket Time	Queue
6	Peak Element V2	Binary Search
7	Binary Tree Traversal	Tree
8	Split Circular Linked List	Linked List
9	Merge Sorted Lists	Linked List

File 8 (String, Queue, Matrix, Heap, Backtracking)

#	Question	Topic
1	Capitalize Words	String
2	Validate Alphanumeric	String
3	Action Logs Stack (SLL)	Stack
4	Flight Gate Queue	Queue
5	Spiral Matrix	Matrix
6	K-th Largest in Stream	Heap
7	Column Sum	Matrix
8	Rat in a Maze	Backtracking
9	Game Simulation	Simulation

File 9 (Sorting, DP, Hashing, Two-Pointer)

#	Question	Topic
1	Insertion Sort Energy V2	Sorting
2	Bubble Sort Swaps	Sorting
3	Server Log Analysis	Hashing
4	Non-Adjacent Max Sum	DP
5	Longest Subarray Sum K	Hashing
6	Sort Binary Array	Two-Pointer
7	Move Zeroes V2	Two-Pointer
8	Sorted Union	Linked List
9	Sorted Intersection	Linked List

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🎓 Topics Covered

• Array: Manipulation, Search, Statistics
• String: Parsing, Encoding, Validation
• Linked List: Reversal, Merge, Split
• Stack: Expression Evaluation, Bracket Matching
• Queue: Simulation, Reversal
• Tree: Traversals, BST Operations
• Matrix: Search, Spiral, Multiplication
• Binary Search: Variants
• Two-Pointer: Sorting, Partitioning
• Hashing: Frequency, Unique Elements
• DP: Max Sum, Optimization
• Backtracking: Pathfinding
• Heap: K-th Element, Streaming

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💡 Tips

1. Start with easier topics (Array, String) before complex ones (DP, Backtracking)
2. Read the algorithm hint if stuck
3. Try similar questions for more practice
4. Time yourself to simulate exam conditions

Good luck! 🚀