DSA Python 2025 – Why Use Priority Queue and not Queue in Dijkstra’s Algorithm? | Part 146

🚀 Welcome to Part 146 of Code & Debug’s DSA Python Course 2025!

In this session, we answer a very important and commonly asked question:

❓ “Why do we use a Priority Queue in Dijkstra’s Algorithm instead of a normal Queue?”

🔍 What you’ll learn:
✅ What goes wrong if you use a normal queue in Dijkstra
✅ How the priority queue helps always pick the minimum distance node
✅ Real-world example & dry run comparisons
✅ Why Dijkstra with a normal queue breaks the greedy property
✅ Time Complexity: O(E log V) of PQ-based approach – full breakdown
✅ Interview-level clarity on why heap is crucial

📄 Topics Covered:
• Dijkstra with Queue: Wrong outputs
• Priority Queue (Min Heap): Correctness + Efficiency
• heapq in Python
• Detailed comparison: Queue vs PQ
• Why O(E log V) is optimal

📚 Complete Python DSA Playlist & Sheet:
https://docs.google.com/spreadsheets/d/1AWE15Fy3wD2iqu2vjK_R7cCiuvSsjYQclcdZmHpF66o/edit?usp=sharing

🚀 Master DSA from Scratch:
https://codeanddebug.in/course/zero-to-hero-python-dsa

💡 Free Problem-Solving Masterclass (Leetcode-Based):
https://codeanddebug.in/course/master-dsa-with-leetcode

👀 Still using a queue in Dijkstra? Let’s fix that today.
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