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Advanced · Module 16 · Lesson 4 of 4

Huffman coding

Huffman coding gives frequent symbols short bit codes and rare ones long codes, with no code a prefix of another. Repeatedly merging the two rarest subtrees in a heap builds the provably shortest such code.

Pro — members onlyAbout 15 minutes

By the end you can

  • Explain prefix-free codes and why they can be decoded without separators
  • Build a Huffman tree with a min-heap, read off the codes and compute the encoded size
  • Explain why merging the two rarest symbols is optimal, and where Huffman coding is used

Builds on Scheduling and intervals, Top-k and merging streams.

01 · A question first

Text is usually stored with a fixed number of bits per character, but in English the letter e is more than a hundred times as common as z. Giving common letters short codes saves space, but how do you choose codes so that a stream of bits can still be split back into letters unambiguously, and the total is as short as possible?

Make a guess before you read on.

02 · The idea

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What's inside

  • Variable-length codes
  • Huffman's algorithm
  • Why the greedy merge is optimal
  • Huffman in the real world
  • Limits
  • Pseudocode & Multi-Language Implementations (C++, Java, Python)
  • Complexity Derivation, Edge Cases & Common Mistakes

03 · Practice

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