9 replies to this topic

[toto_7]

Ok, im completly confused with this algorithm.
I have an algorithm which adds together the numeric values of the first three letters from array with 15 names. How i can find, how long does the storage array need to be?

[wim DC]

Without seeing or better explaining the algorithm it's hard to tell.

Out of your current text I deduct that you transform an array of names into a number...

[toto_7]

I have an array of 15 names

Arthur

Barry

Francis...

First create an index array whose elements refer to the position in my array of the first key which starts with a given letter.
Then create another array which holds pointers to chains holding keys for the different initial letters.
And now i have to improve the previous method by converting the key to an index using hashing function (adds together first 3 letters)
I have to find how long does the new storage array need to be

[wim DC]

Quote

First create an index array whose elements refer to the position in my array of the first key which starts with a given letter.
Then create another array which holds pointers to chains holding keys for the different initial letters.
And now i have to improve the previous method by converting the key to an index using hashing function (adds together first 3 letters)
I have to find how long does the new storage array need to be

I lost you at line 1 :P

[toto_7]

Ok lets try again :P

At the beggining i have a simple array with 15 names(Arthur, Barry, Francis, Garry...)

Then using an index array that its element points to the first name of each first letter (ex. if i have Harry and Henry, index's array element will point only on Harry) So index array will have elements like (0,3,-1,-1,5...) where -1 is when names array doesnt has name which starting with that letter.
So..we can say
IndexArr[0]->A
IndexArr[1]->B
IndexArr[2]->C etc..

Now i have to use the hashing algorithm to improve the efficiency of method above. Each key converted to an index using a hashing function, which adds the numeric values of the first three letters.

[wim DC]

Okay assume 4 names only
Names array = {"dalc", "aalc", "balc", "calc"}
Index array = {1, 2, 3, 0, -1, -1, ...}
And now instead of doing it with 1 letter you wanna have 3?
So
IndexArr[0] -> AAA
IndexArr[1] -> AAB
IndexArr[2] -> AAC
....
And you need to know the total size of indexArr?

[toto_7]

Names are in alphabetic row

Names array = {"aalc", "balc", "calc", "dalc"}
Index array = {0, 1, 2, 3, -1, -1, ...}

And are the three first letters each name (aal, bal, cal, dal)
Yes, asking the total size. Im really confused with hashing algorithm, so may be the way i understant it to be wrong

[Warrior]

its unclear what you are trying to do?
maybe it will help if you post the whole program...perhaps there is an other way around

[toto_7]

Ok, i will try one more time. To store the first letter from a word, i need an array of size 26, now to store the first three letters from a word, what the size of the array will be using a simple hashing function?

[wim DC]

So you need to create an array of

AAA

AAB

AAC

AAD

...

DEA

DEB

DEC

...

ZZZ

And you just need to know the total size of that?
I think that's just 26³