PillPilot - Medication Tracker

DSA Mini Project - 3rd Semester

What is this?

A medication management system built in C that helps track medicines and reminds you when to take them. Made for our Data Structures course to understand how different data structures work in real applications.

Data Structures Used

1. HashMap - Stores medicines with fast O(1) lookup by ID
2. Priority Queue (Min-Heap) - Keeps schedule sorted by time automatically
3. Linked List - Tracks medication history chronologically

How to Run

Linux/Mac:

gcc pillpilot.c -o pillpilot
./pillpilot

Windows:

gcc pillpilot.c -o pillpilot.exe
pillpilot.exe

Online Compiler:

• Go to https://www.onlinegdb.com/online_c_compiler
• Paste the code and click Run

Features

• Add medicines with name, dosage, time, and instructions
• View all medicines (HashMap demo)
• View today's schedule sorted by time (Priority Queue demo)
• Mark medicines as taken or missed
• View medication history (Linked List demo)
• See statistics and adherence rate
• Search medicine by ID
• Delete medicine

Why These Data Structures?

HashMap vs Array

• Array: O(n) search time - have to check each medicine one by one
• HashMap: O(1) average search time - jump directly to the medicine using ID
• Used hash function with linear probing for collision handling

Priority Queue vs Sorting Array

• Sorting entire array every time: O(n log n)
• Priority Queue insertion: O(log n)
• Priority Queue keeps medicines sorted by time automatically
• Min-heap structure - smallest time always at root

Linked List for History

• Insert at head is O(1) - very fast
• Don't need fixed size like arrays
• Perfect for adding new entries (most recent first)

Time Complexity

Operation	Time	Data Structure
Add medicine	O(1) avg	HashMap
Search by ID	O(1) avg	HashMap
Delete medicine	O(1) avg	HashMap
Add to schedule	O(log n)	Priority Queue
Add history entry	O(1)	Linked List
View history	O(n)	Linked List

Sample Output

Enter choice: 1
Enter medicine name: Paracetamol
Enter dosage: 500mg
Enter time: 08:30
Enter instructions: After breakfast

✓ Medicine added successfully! ID: 3421

Enter choice: 7
=== TODAY'S STATISTICS ===
Total Medicines: 2
Medicines Taken Today: 1
Medicines Missed Today: 0
Adherence Rate: 100.0%

Known Limitations

• Data is lost when program exits (no file saving yet)
• Hash table has fixed size of 100 entries
• Time input format not validated
• Priority queue display not fully sorted (TODO)

Future Improvements

• Add file I/O to save/load data
• Input validation for time format
• Fix priority queue display sorting
• Maybe add GUI if possible in C

Real World Use

Around 50% of patients forget to take their medicines. This system can help by:

• Automatic time-based reminders
• Tracking what was taken/missed
• Calculating adherence rates
• Could be scaled up for hospitals or clinics

What I Learned

• How hash tables work and handle collisions
• Min-heap implementation for priority queues
• When to use linked lists vs arrays
• Time complexity trade-offs between data structures
• Combining multiple data structures in one program

Project Files

• pillpilot.c - Main source code
• test_cases.txt - Test scenarios and expected outputs
• README.md - This file

Deets

Course: Data Structures & Applications (22AI34)
Semester: 3
Department: Artificial Intelligence & Machine Learning

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Built for DSA course project - Academic Year 2025-26