fixed bug for paired character problem

[Priyanshu-2005]

@akhilender-bongirwar

solved issue #18

[akhilender-bongirwar]

@Priyanshu-2005, provide the screenshots for output.

[Priyanshu-2005]

@akhilender-bongirwar logic initialize an array of 256 length using loop traverse through the string(only even indices according to the question) and count the freq of characters now add the minimum of small letter frequency or capital letter frequency to the counter variable which indicates the no. of pairs possible of that alphabet (even positions only and 0 index according to the problem statement )

changes made used array instead of unordered map started loop from i=0 instead of i=1 loop goes till i<2n instead of i<2(n-1) also the logic inside the for loop changed

[Priyanshu-2005]

[Priyanshu-2005]

@akhilender-bongirwar added the screenshots and logic