docs: README

README.md

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+# Programming snippets
+
+Snippets to perform non-trivial operations in some programming languages.
+

prefix_tree/fruits.txt

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+apple
+apricot
+avocado
+banana
+berry
+blackberry
+blood orange
+blueberry
+boysenberry
+breadfruit
+cantaloupe
+cherry
+citron
+citrus
+coconut
+crabapple
+cranberry
+current
+date
+dragon fruit
+durian
+elderberry
+fig
+grape
+grapefruit
+guava
+honeydew
+jackfruit
+kiwi
+kumquat
+lemon
+lime
+lingonberry
+loquat
+lychee
+mandarin orange
+mango
+marionberry
+melon
+mulberry
+nectarine
+orange
+papaya
+passion fruit
+peach
+pear
+persimmon
+pineapple
+plantain
+plum
+pluot
+pomegranate
+pomelo
+prune
+quince
+raisin
+raspberry
+star fruit
+strawberry
+tangelo
+tangerine
+ugli fruit
+watermelon

prefix_tree/prefix_tree.py

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+# Example of a prefix tree implementation in python 
+# Trie data-structure implementation
+# https://en.wikipedia.org/wiki/Trie
+# original date: 2021-12-03
+
+import fileinput
+
+def load_from_stdin():
+  inp = fileinput.input()
+  words = []
+  for line in inp:
+    word = line.strip()
+    # non case sensitive
+    words.append(word.lower())
+  return words
+
+# create the trie data structure
+def build_trie(words):
+  if words == []:
+    return {}
+  nodes = {}
+  for w in words:
+    if w[0] not in nodes:
+      nodes[w[0]] = []
+    if len(w[1:]) > 0:
+      nodes[w[0]].append(w[1:])
+  for letter in nodes:
+    nodes[letter] = build_trie(nodes[letter])
+  return nodes
+
+def get_sub_tree(nodes, pattern):
+  if pattern == '': return nodes
+  if pattern[0] not in nodes: return {}
+  return get_sub_tree(nodes[pattern[0]], pattern[1:])
+
+def get_strings(nodes):
+  words = []
+  for k in nodes.keys():
+    if nodes[k] == {}:
+      words += [ k ]
+    else:
+      res = get_strings(nodes[k])
+      words += [ k + x for x in res]
+  return words
+
+def search_in_trie(nodes, pattern):
+  nodes = get_sub_tree(nodes, pattern)
+  words = get_strings(nodes)
+  return [ pattern + x for x in words ]
+
+def main():
+  words = load_from_stdin()
+  res = build_trie(words)
+  # test matching prefix "ma"
+  sugg = search_in_trie(res, 'ap')
+  print(sugg)
+
+main()