mirror of
https://github.com/donnemartin/interactive-coding-challenges.git
synced 2024-03-22 13:11:13 +08:00
76 lines
2.3 KiB
Python
76 lines
2.3 KiB
Python
from collections import OrderedDict
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class Node(object):
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def __init__(self, key, parent=None, terminates=False):
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self.key = key
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self.terminates = False
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self.parent = parent
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self.children = {}
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class Trie(object):
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def __init__(self):
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self.root = Node('')
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def find(self, word):
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if word is None:
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raise TypeError('word cannot be None')
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node = self.root
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for char in word:
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if char in node.children:
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node = node.children[char]
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else:
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return None
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return node if node.terminates else None
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def insert(self, word):
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if word is None:
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raise TypeError('word cannot be None')
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node = self.root
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parent = None
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for char in word:
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if char in node.children:
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node = node.children[char]
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else:
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node.children[char] = Node(char, parent=node)
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node = node.children[char]
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node.terminates = True
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def remove(self, word):
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if word is None:
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raise TypeError('word cannot be None')
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node = self.find(word)
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if node is None:
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raise KeyError('word does not exist')
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node.terminates = False
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parent = node.parent
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while parent is not None:
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# As we are propagating the delete up the
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# parents, if this node has children, stop
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# here to prevent orphaning its children.
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# Or
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# if this node is a terminating node that is
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# not the terminating node of the input word,
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# stop to prevent removing the associated word.
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if node.children or node.terminates:
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return
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del parent.children[node.key]
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node = parent
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parent = parent.parent
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def list_words(self):
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result = []
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curr_word = ''
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self._list_words(self.root, curr_word, result)
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return result
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def _list_words(self, node, curr_word, result):
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if node is None:
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return
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for key, child in node.children.items():
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if child.terminates:
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result.append(curr_word+key)
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self._list_words(child, curr_word+key, result) |