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First unique character in a string
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15 mins
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First unique character in a string

Contributed by
Dhruv Sharma
Medium
yellow-spark
0/80
Avg time to solve 15 mins
Success Rate 85 %
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Problem Statement

You are given a string S of length N. Your task is to find the index(considering 1-based indexing) of the first unique character present in the string. If there are no unique characters return -1.

Note

A unique character in a string is the character that appears only once in the string. For example, ‘h’, ‘e’, and ‘o’ are the unique characters in the string “hello”.
Detailed explanation ( Input/output format, Notes, Constraints, Images )
Sample Input 1 :
2
16
codingninjascode
24
practicepracticepractice
Sample Output 1:
6
-1
Explanation for Input 1:
For the first subtask the explanation is given in the problem statement. 

For the second subtask there are no unique characters so ans is -1.
Sample Input 2 :
3
19
palindromemordnilap
9
notunique
7
caaabbc
Sample Output 2:
10
2
-1
Explanation for Input 2:
For the first subtask, every character except ‘e’ occurs 2 times so we print the index of e that is 10. 

For the second subtask, the characters ‘o’ , ‘t’ , ‘e’ , ‘i’ and ‘q’ are unique but ‘o’ occurs before all the other unique characters .

For the third subtask, all the characters are not unique so we return -1.
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