What Is Huffman Coding in Data Structure?


Heather Bennett

What Is Huffman Coding in Data Structure?

Huffman coding is a popular data compression algorithm used in computer science and information theory. It is named after David A. Huffman, who first proposed the technique in his 1952 paper “A Method for the Construction of Minimum-Redundancy Codes”.

Huffman coding is widely used in applications that require efficient storage and transmission of data.

Why Do We Need Huffman Coding?

Data compression is essential in various fields where reducing the size of data is crucial. By compressing data, we can optimize storage space, reduce transmission time, and save bandwidth.

Huffman coding plays a significant role in achieving efficient compression by creating variable-length prefix codes, where frequently occurring characters are assigned shorter codes than less frequent ones.

How Does Huffman Coding Work?

Huffman coding uses a character frequency table to build an optimal Huffman tree. The process involves the following steps:

  • Create a frequency table: Count the occurrence of each character in the given input data.
  • Create a priority queue: Initialize a priority queue with nodes representing each character and its frequency. The node with the lowest frequency has the highest priority.
  • Merge nodes: Repeat until only one node remains in the priority queue:
    • Select two nodes with the lowest frequency from the priority queue.
    • Create a new node with their combined frequency as its value.
    • The two selected nodes become children of the new node.
    • Add the new node back to the priority queue.
  • The last remaining node in the priority queue is the root of the Huffman tree.

Constructing Huffman Codes

Once we have built the Huffman tree, we can assign unique binary codes to each character by traversing the tree. The left branch represents a 0, and the right branch represents a 1.

The path from the root to a leaf node gives us the binary code for that character. As we move left or right in the tree, we append 0s or 1s to form a unique code.


Let’s say we have a string “HELLO WORLD”. By applying Huffman coding, we can compress this string as follows:

  • H: 00
  • E: 010
  • L: 11
  • O: 011
  • W: 0010
  • R: 0011
  • D: 1000

So, our compressed string becomes “00 010 11 11 011 0010 0011 1000”.

Decoding Huffman Codes

To decode a compressed message encoded with Huffman coding, we start from the root of the Huffman tree and follow the binary digits of the encoded message. Whenever we encounter a ‘0’, we move left in the tree, and when we encounter a ‘1’, we move right.

Once we reach a leaf node, that character is decoded. By repeating this process for each code segment, we can reconstruct the original data.


Huffman coding is a powerful technique for data compression. It effectively reduces the size of data by assigning shorter codes to frequently occurring characters.

By understanding the concepts behind Huffman coding and implementing it in various applications, we can achieve efficient storage and transmission of data.

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