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Trie

Trie is a data structure belonging to n-ary trees, which is designed for some specific questions, such as, prefix of strings. (If you have never known what binary tree is, maybe you can check binary tree first before read more about Trie). The fact that there are only 26 different letters greatly reduce the possible choices for each position. Or to make it clear, for each position, there are 26 different choices. In mathematics, it seems to be very large (height^26 for the full tree), but in reality, it is rare to be a full tree for the set of meaningful strings (needs at least height^26 strings to be a full tree!), since the height or length of English words are less than 10 in most cases. Therefore, it is popular in string matching or related operations.

Please be noted that the trie structure is not only limited to strings, the same idea can be extended to other data types, such as integer (then it becomes a binary tree, since for bit, there are only two possible values).

In the code part, there are usually three steps:

1. define the trie node structure;

2. build trie;

3. function for searching the trie (or extract information needed).


Question List


Upper Layer


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