0208-Implement-Trie-(Prefix-Tree).py

'''
Implement a trie with insert, search, and startsWith methods.

Example:

Trie trie = new Trie();

trie.insert("apple");
trie.search("apple");   // returns true
trie.search("app");     // returns false
trie.startsWith("app"); // returns true
trie.insert("app");
trie.search("app");     // returns true
Note:

You may assume that all inputs are consist of lowercase letters a-z.
All inputs are guaranteed to be non-empty strings.
'''
class Trie:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.dic = {}

    def insert(self, word):
        """
        Inserts a word into the trie.
        :type word: str
        :rtype: void
        """
        cur = self.dic
        for c in word:
            if c not in cur:
                cur[c] = {}
            cur = cur[c]
        cur['end'] = {}

    def search(self, word):
        """
        Returns if the word is in the trie.
        :type word: str
        :rtype: bool
        """
        cur = self.dic
        for c in word:
            if c in cur:
                cur = cur[c]
            else:
                return False
        if 'end' in cur:
            return True
        return False


    def startsWith(self, prefix):
        """
        Returns if there is any word in the trie that starts with the given prefix.
        :type prefix: str
        :rtype: bool
        """
        cur = self.dic
        for c in prefix:
            if c in cur:
                cur = cur[c]
            else:
                return False
        return True

# Your Trie object will be instantiated and called as such:
# obj = Trie()
# obj.insert(word)
# param_2 = obj.search(word)
# param_3 = obj.startsWith(prefix)