Python Forum

Hi,
I have to delete minimum number of character in a string.
I saw that there is Counter but I don't know how to use it.
This is my code for now:

word  = "abecedario alpaca"
char = ''
word_list = []
#add a string into a list 
for c in word:
  word_list.append(c)
#print(word_list)
#a counter that check if inside a list there is a char 
count = 0
for counter in word_list: #for any elements of list --> is there char? 
  if counter == char:
    count = count + 1 #counter 

print(count)

This is text :

Quote:Given a string s consisting of n lowercase letters, you have to delete the minimum number of characters from s so that every letter in s appears a unique number of times. We only care about the occurrences of letters that appear at least once in result.

Regards,
RavCoder

Key here is "unique number of times". And, you are to delete the least number of characters possible. I know how I would approach, but interested in your overall plan for the script.

Take the imaginary word "pneumonaoultramicroscoapicsailaicovolcanoconiosillls". In this word, the letters a, l, c, i appear 6 times. Let R be the resulting word after you have removed the necessary characters. In this resulting word, the letters a, l, c, i appear at most 6 times and each a different number of times. It doesn't matter which of these 4 characters appears more or less than another because it doesn't change the count of removed characters if we choose to remove 3 a's or 3 i's. So we can as well suppose that we need to remove at least 1 l, 2 c's and 3 i's.

You can repeat this procedure as long as there are characters that appear the same number of times.

So a-l-c-i will be (in any order) 6-5-4-3 leaving only 2 and 1 for the remaining letters. The source word must be chosen carefully.

Bottom line - counting the incidence of the letters is just the beginning.

jefsummers Wrote:So a-l-c-i will be (in any order) 6-5-4-3 leaving only 2 and 1 for the remaining letters.

No, the procedure is repeated as long as there are letters having the same number of occurrences.

"you have to delete the minimum number of characters from s so that every letter in s appears a unique number of times" makes me wonder what should happen with string 'abc'

I don't know exactly how to do it, but I think I have to declare the word I want to search first in

 char = "character that I want to search" 

Another question - is non-printable character in context of this assignment a character?

Using string in original post:

>>> import collections
>>> word  = "abecedario alpaca"
>>> counts = collections.Counter(word)
>>> counts
Counter({'a': 5, 'e': 2, 'c': 2, 'b': 1, 'd': 1, 'r': 1, 'i': 1, 'o': 1, ' ': 1, 'l': 1, 'p': 1})

How should one interpret the constraint: 'We only care about the occurrences of letters that appear at least once in result.'.

perfringo Wrote:what should happen with string 'abc'

I think 'abc' --> 'a'

The assignment uses the term "letters", so although wrong to assume, I would think only letters count.
Understanding the answer and process first, then coding,
Using the string in the original post and the counts as in perfringo's post, you could have 5 a's, 2 e's, 1 c and that's it. Everything else would be deleted as the count would duplicate (alternative answer 5 a's, 2 c's, 1 e).

If we agree that this is the answer, then can advise regarding the coding.