113 lines
2.0 KiB
Markdown
113 lines
2.0 KiB
Markdown
---
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layout: page
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title: Implement Trie
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last_solved: 2020-06-30
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category: Attempted
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leetcode_url: https://leetcode.com/problems/implement-trie-prefix-tree/
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status: Attempted
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---
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Problem
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-------
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```
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Implement a trie with insert, search, and startsWith methods.
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Example:
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Trie trie = new Trie();
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trie.insert("apple");
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trie.search("apple"); // returns true
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trie.search("app"); // returns false
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trie.startsWith("app"); // returns true
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trie.insert("app");
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trie.search("app"); // returns true
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```
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Solution
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----------
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This code doesn't work correctly. Need to check it and debug it.
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[source](https://www.youtube.com/watch?v=KX2GdDZPxQA)
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{% highlight python %}
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class Node:
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def __init__(self):
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self.children = {} # the children that this node points to
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self.endofword = False
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class Trie:
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def __init__(self):
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self.root = Node()
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def insert(self, word: str) -> None:
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ptr = self.root
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for letter in word:
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if letter not in ptr.children:
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ptr.children[letter] = Node()
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# traverse down the tree
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ptr = ptr.children[letter]
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ptr.endofword = True
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def search(self, word: str) -> bool:
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ptr = self.root
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for letter in word:
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if letter not in ptr.children:
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return False
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ptr = ptr.children[letter]
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# check end of word?
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if ptr.endofword:
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return True
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else:
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return False
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def startsWith(self, prefix: str) -> bool:
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ptr = self.root
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for letter in prefix:
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if letter not in ptr.children:
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return False
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ptr = ptr.children[letter]
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return True
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trie = Trie();
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output = []
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output.append( trie.insert("apple") )
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output.append( trie.search("apple") )
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output.append( trie.search("app") )
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output.append( trie.startsWith("app") )
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output.append( trie.insert("app") )
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output.append( trie.search("app") )
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print(output)
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{% endhighlight %}
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![image1]() |