[LeetCode]first unique character in a string (완료)

[yeonghwanjeon]

• 문제 링크

• 문제 풀이

  • Counting sort 개념 활용

  • Hash map 문제 활용

    class Solution(object):
    def firstUniqChar(self, s):
    """
    :type s: str
    :rtype: int
    """
    if not s : return -1
    
    c_dict = {}
    for c in s :
        if c in c_dict :
            c_dict[c] += 1
        else :
            c_dict[c] = 1
    
    result = -1
    for i, c in enumerate(s) :
        if c_dict[c] == 1 :
            if result == -1 :
                result = i
            else :
                result = min(result, i)
    
    return result

[yeonghwanjeon]

• 다른 풀이

  • Collections를 잘 활용할 수 있어야함

  • Counter 쓰면 ordered 되어 나오는 듯

    class Solution:
    def firstUniqChar(self, s):
    """
    :type s: str
    :rtype: int
    """
    # build hash map : character and how often it appears
    count = collections.Counter(s)
    
    # find the index
    index = 0
    for ch in s:
        if count[ch] == 1:
            return index
        else:
            index += 1       
    return -1