[Arrays] firstNotRepeatingCharacter - Amazon

Problem:

Given a string s consisting of small English letters, find and return the first instance of a non-repeating character in it. If there is no such character, return '_'.

 

Example

• For s = "abacabad", the output should be
  firstNotRepeatingCharacter(s) = 'c'.

  There are 2 non-repeating characters in the string: 'c' and 'd'. Return c since it appears in the string first.

• For s = "abacabaabacaba", the output should be
  firstNotRepeatingCharacter(s) = '_'.

  There are no characters in this string that do not repeat.

-Summary-

1. Used a linear search algorithm.

2. If any number that is not in the temp_set and not exists in the rest of the string, it is the only one character.

3. If not found, return '_'

 

사람들이 풀어놓은 답을 봤더니 파이썬의 rindex() 라는 함수를 이용해서 정말 깔끔하게 구현할수 있었다. 오늘도 새로운 파이썬의 method를 배운다.

def firstNotRepeatingCharacter(s):
    for c in s:
        if s.index(c) == s.rindex(c):
            return c
    return '_'

 

 

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