September 2017 Update

Task/Huffman-coding/CoffeeScript/huffman-coding-1.coffee

@@ -1,85 +0,0 @@
-huffman_encoding_table = (counts) ->
-  # counts is a hash where keys are characters and
-  # values are frequencies;
-  # return a hash where keys are codes and values
-  # are characters
-
-  build_huffman_tree = ->
-    # returns a Huffman tree.  Each node has
-    #   cnt: total frequency of all chars in subtree
-    #   c: character to be encoded (leafs only)
-    #   children: children nodes (branches only)
-    q = min_queue()
-    for c, cnt of counts
-      q.enqueue cnt,
-        cnt: cnt
-        c: c
-    while q.size() >= 2
-      a = q.dequeue()
-      b = q.dequeue()
-      cnt = a.cnt + b.cnt
-      node =
-        cnt: cnt
-        children: [a, b]
-      q.enqueue cnt, node
-    root = q.dequeue()
-
-  root = build_huffman_tree()
-
-  codes = {}
-  encode = (node, code) ->
-    if node.c?
-      codes[code] = node.c
-    else
-      encode node.children[0], code + "0"
-      encode node.children[1], code + "1"
-
-  encode(root, "")
-  codes
-
-min_queue = ->
-  # This is very non-optimized; you could use a binary heap for better
-  # performance.  Items with smaller priority get dequeued first.
-  arr = []
-  enqueue: (priority, data) ->
-    i = 0
-    while i < arr.length
-      if priority < arr[i].priority
-        break
-      i += 1
-    arr.splice i, 0,
-      priority: priority
-      data: data
-  dequeue: ->
-    arr.shift().data
-  size: -> arr.length
-  _internal: ->
-    arr
-
-freq_count = (s) ->
-  cnts = {}
-  for c in s
-    cnts[c] ?= 0
-    cnts[c] += 1
-  cnts
-
-rpad = (s, n) ->
-  while s.length < n
-    s += ' '
-  s
-
-examples = [
-  "this is an example for huffman encoding"
-  "abcd"
-  "abbccccddddddddeeeeeeeee"
-]
-
-for s in examples
-  console.log "---- #{s}"
-  counts = freq_count(s)
-  huffman_table = huffman_encoding_table(counts)
-  codes = (code for code of huffman_table).sort()
-  for code in codes
-    c = huffman_table[code]
-    console.log "#{rpad(code, 5)}: #{c} (#{counts[c]})"
-  console.log()

Task/Huffman-coding/CoffeeScript/huffman-coding-2.coffee

@@ -1,34 +0,0 @@
-> coffee huffman.coffee
----- this is an example for huffman encoding
-000  : n (4)
-0010 : s (2)
-0011 : m (2)
-0100 : o (2)
-01010: t (1)
-01011: x (1)
-01100: p (1)
-01101: l (1)
-01110: r (1)
-01111: u (1)
-10000: c (1)
-10001: d (1)
-1001 : i (3)
-101  :   (6)
-1100 : a (3)
-1101 : e (3)
-1110 : f (3)
-11110: g (1)
-11111: h (2)
-
----- abcd
-00   : a (1)
-01   : b (1)
-10   : c (1)
-11   : d (1)
-
----- abbccccddddddddeeeeeeeee
-0    : e (9)
-1000 : a (1)
-1001 : b (2)
-101  : c (4)
-11   : d (8)