First non repeating character

Posted: 1 Dec, 2020
Difficulty: Easy

PROBLEM STATEMENT

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Ninja is now bored with numbers and is now playing with characters but hates when he gets repeated characters. Ninja is provided a string, and he wants to return the first unique character in the string.The string will contain characters only from the English alphabet set, i.e., ('A' - 'Z') and ('a' - 'z'). If there is no non-repeating character, print the first character of the string. If there is no non-repeating character, return the first character of the string.

Input Format:
The first line contains a single integer T representing the number of test cases. 

The first and the only line of each test case will contain the input string.
Output Format:
For each test case, print a character denoting the first non-repeating character in the input string.
Note:
You do not need to print anything; it has already been taken care of. Just implement the given function. 
Constraints:
1 <= T <= 10
1 <= Length of Input String <= 10^4

Time Limit: 1 sec 
Approach 1

 We will traverse the whole array and check if that element previously occurred or not.

 

The steps are as follows:

  • We will iterate over all the elements of the array, i.e., i = 0 to i = N - 1:
    • We will iterate over all the elements of the array excluding the present element, i.e., j = 0 to i = N - 1:
      • If we get that for no j, S[i] equals S[j], then we return S[i].
  • We will return the first character of the string if the loop completes and no answer is returned.
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