thanks robin. i have however noticed in general that a hash table invariably has performance issues in comparison to a trie when storing a large dataset of strings. i guess this is because a trie does guarantee constant time lookup given that in normal circumstances the max length of the string is fixed. a hash table on the other hand does not guarantee constant time lookup due to collisions. another advantage with an optimized trie is that the key does not have to be duplicated. so if there are two keys - "bhavin" and "bhatia" - the first 3 characters do not need to be stored twice making the structure relatively more compact (offcourse this only applies to one of the space-optimized trie structures. in a regular trie since each node would store 26 buckets the total space consumed may actually be considerably higher). lastly i would assume since hash tables are sparse by nature they would take up extra space that tries and trees otherwise do not

- Bhavin