Github link huffman 實作我使用了幾個 data structure 1. map 2. min heap 3. tree 主要分3個階段完成huffman coding 所需要的 data structure，對於之後的encode 跟decode是很重要的 Phase 1 : read file and record the frequency of each character (unordered_map) Phase 2 : using map to construct min heap (min heap) Phase 3 : using min-heap to create huffman coding tree (tree) 在講 encode 前，先說明huffman的概念 Concept : wiki link 1. 無失真壓縮 2. 常出現的字，用最少的bit來描述 3. 應用在檔案壓縮 encode algorithm : 1. construct huffman coding tree if there are more than 2 in min heap, we dequeue two item. add these two frequency and create a new node as virtual item. make these two item be new node's left/right child. then push back to min-heap go repeat until there are no more than 2 illustrated : https://www.google.com/search?q=huffman+coding&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiQ4tKOlO7iAhXIw7wKHfESDUAQ_AUIECgB&biw=1024&bih=462#imgrc=QMXyN8ycoMLfrM: 2...