[Solved] Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1.

Question

Given a string sfind the first non-repeating character in it and return its index. If it does not exist, return -1.

Example 1:

Input: s = "leetcode"
Output: 0

Example 2:

Input: s = "loveleetcode"
Output: 2

Example 3:

Input: s = "aabb"
Output: -1

Constraints:

  • 1 <= s.length <= 105
  • s consists of only lowercase English letters.

Python Solution

class Solution:
    def firstUniqChar(self, s: str) -> int:
        d={}
        for i in s:
            if i not in d:
                d[i]=1
            else:
                d[i]+=1

        for k,v in d.items():
            if v==1:
                return s.index(k)
        return -1
Abhishek Sharma
Abhishek Sharma

Started my Data Science journey in my 2nd year of college and since then continuously into it because of the magical powers of ML and continuously doing projects in almost every domain of AI like ML, DL, CV, NLP.

Articles: 514

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