How to find unique chars count of a string in javascript?

[suchetapatra]

Unique characters:

Eg: If 'unique' is a keyword, the unique characters count should be = 4

[jkmyoung]

edit-- Brute force is probably the most suitable for you. If you're not interested in algorithms, ignore the rest of the post.

I suggest using a bubble sort like algorithm. If you're bubbling and one
character matches another, 'delete' that character.

Sort the first 1 character.
Then sort the first 2 characters.
Then sort the first 3 characters.

This requires keeping track of 3 index variables.
uniqueChars, compareIndex, nextCharacter

eg, take unique.

1'st iteration.
u : uniqueChars = 1
u + n => nu: uniqueChars = 2
nu + i => inu: uniqueChars = 3
inu + q => inqu: uniqueChars = 4
inuq + u => inqu: uniqueChars = 4
inqu + e => einqu: uniqueChars = 5

Once you have this working, you could use a binary search like algorithm to speed up the time.

Another example: pineapple
p
p+i -> ip
ip+n -> inp
inp + e -> einp
einp + a -> einpa
einpa + p -> einpa
einpa + p -> einpa
einpa + l -> eilnpa
eilnpa + e -> eilnpa 6.
=========
If you don't like this method you could always do the lazy method.

[Dormilich]

is that something like a Binary Heap?