firstUniqueCharacter.md

Problem statement: Given a string str, find the index of first non-repeating(unique) character within it. If the unique character doesn't exist, return -1.

Note: The given string contains only lowercase English letters.

Examples:

Example 1:

Input: str = "zeep"

Output: 0

Example 2:

Input: str = "mama"

Output: -1

Algorithmic Steps This problem is solved using a hashing data structure to find the occurrences of each character and determine the index of the first unique character in a string.

1. Define a map variable(charCount) to keep track of character counts.

2. Iterate over the given string(str) and store the character count.

3. Iterate over the string again, return the index if the character count is equals to one

4. Return -1 indicating that no unique character found.

Time and Space complexity: This algorithm has a time complexity of O(n), Where n is the length of the string. This is because we traverse the string twice to find the index position of first unique character.

Here, it takes time complexity of O(1). This is because the character count variable holds maximum of 26 lowercase characters.