Find First Unique Character in a String | Programming Tutorials

In this tutorial, I have explained how to find first unique character in a string in O(n) time complexity.

Given an input string. Write a code to find the first non-repeating or unique character in it and return it's index. If it doesn't exist then return -1.

In this tutorial, i have explained multiple approaches and it's java code to solve this problem.

For example -

Example 1-

Input = "java"

Output = 0 ( j is the first non-repeating character)

Example 2-

Input = "character"

Output = 1 (h is the first non-repeating character)


Example 3 -

Input = "calculate"

Output = 4 ( u is the first non-repeating character)

[sujatatiwari]

Hi,
Please check the voice quality of your video. It's taking pauses in between the videos. Otherwise, your way of explanation is amazing.

[sureshpathak]

I think LinkedHashMap could be a better solution as it will maintain the sequence also.