Figure indicates one source of inefficiency for tries: the path to “REAR” and “REP” leads...

Figure indicates one source of inefficiency for tries: the path to “REAR” and “REP” leads through a node that has just one child. For longer identical prefixes, the number of such nodes can be even longer. Implement a spell checker with a variation of the trie, called the multiway Patricia tree (Morrison 1968), The original Patricia tree was a binary tree, and the tests were made on the level of bits which curtails the paths in the trie by avoiding nodes with only one child. It does this by indicating for each branch how many characters should be skipped to make a test. For example, a trie from Figure is transformed into a Patricia tree in Figure. The paths leading to the four words with prefix “LOGG” are shortened at the cost of recording in each node the number of characters to be omitted starting from the current position in a string. Now, because certain characters are not tested along the way, the final test should be between a key searched for and the entire key found in a specific leaf.

Figure A trie of some words composed of the five letters A, E, I, R, and P. The sharp sign, #, indicates the end of a word, which can be a prefix of another word.