DSA Python 2025 – Word Ladder II | All Shortest Paths Using BFS | Leetcode 126 – Part 130 [Hindi]

🚀 Welcome to Part 130 of Code & Debug’s DSA Python Course 2025!

In this lecture, we tackle Leetcode 126: Word Ladder II, where we’re asked to return all shortest transformation sequences from beginWord to endWord by changing one character at a time. This is an extension of the Word Ladder problem, requiring careful use of level-wise BFS and path tracking.

📚 What you’ll learn in this video:
✅ Modeling the word transformation as a graph
✅ Generating all valid sequences using BFS with queue of lists
✅ Tracking each word only once per level to ensure shortest paths
✅ Smart pruning with wordSet and chosen_words
✅ Time & space complexity analysis

💡 Why is this important?
This problem tests your ability to not just find one shortest path, but enumerate all shortest paths in a graph-like structure — making it highly relevant for interview rounds at top tech companies.

👉 Practice the problem on Leetcode:
🔗 https://leetcode.com/problems/word-ladder-ii/

👉 Refer to the article for better understanding:
🔗 https://codeanddebug.in/blog/word-ladder-ii-leetcode-126/

👉 📄 Access the full YouTube DSA Playlist Sheet (All Questions in Order):
🔗 https://docs.google.com/spreadsheets/d/1AWE15Fy3wD2iqu2vjK_R7cCiuvSsjYQclcdZmHpF66o/edit?usp=sharing

👉 Enroll in this FREE DSA Python course here:
🔗 https://codeanddebug.in/course/master-dsa-with-leetcode

👉 Enroll for Self-Paced Advanced DSA course here:
🔗 https://codeanddebug.in/course/zero-to-hero-python-dsa

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