determine if a string has all unique characters?

Question

Can anybody tell me how to implement a program to check a string contains all unique chars ?

Answer 1

Similarly (and without arrays), use a HASH TABLE!

//psuedo code:

1. go through each char of the string
2. hash the char and look it up in the hash table
3. if the table has the hash, return FALSE // since it's not unique
4. __else store the hash
5. return to step #1 until you're done

Run time is O(n) and memory space is better too since you don't need an array of 256 (asciis)