huffman notes

370/notes/huffman.md

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+# Huffman codes
+
+Covering: Fixed length encoding & Variable length encoding
+
+# Fixed length encoding
+
+consider ascii or unicode, where each symbol is either 8-bit or 16-bits in width.
+
+# Huffman Trees
+
+We create a tree of character frequencies where each node basically has a character and that character's frequency.
+
+```
+struct Node {
+	uint8_t c;
+	size_t frequency;
+	...
+};
+```
+
+Rules of thumb:
+	* The more frequent characters are close to the root
+	* Less frequent characters are found far from the root
+
+We'll end up with a list of nodes which we can throw into a maxheap to build our huffman tree.
+
+General decoding process goes like this:
+
+	1. Get frequencies of all symbols
+	2. Put those frequenncies of symbols into a structure like above
+	3. Build max heap of the node set
+		Keep in mind however that our root should be agnostic so that we can start bit strings with 0|1
+	4. When we reach a leaf we drop that char into the result
+
+