387. First Unique Character in a String

🟩 Easy

Question

Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1.

Examples:

s = "leetcode"
return 0.

s = "loveleetcode",
return 2.

Note: You may assume the string contain only lowercase letters.

Code

from collections import Counter
def firstUniqChar(self, s: str) -> int:
    for k, v in Counter(s).items(): 
    # items() return the list with all dictionary keys with values
        if v == 1:
            return s.index(k)
    return -1

Python Counter Object

cnt = Counter()
for word in ['red', 'blue', 'red', 'green', 'blue', 'blue']:
    cnt[word] += 1
>>> Counter({'blue': 3, 'red': 2, 'green': 1})