Q11:Implement an algorithm to determine if a string has all unique
characters.What if you can not use additional data structures?
Q12:Write code to reverse a C-Style String. (C-String means that “abcd”
is represented as five characters, including the null character.)
Q13:Design an algorithm and write code to remove the duplicate
characters in a string without using any additional buffer. NOTE: One
or two additional variables are fine. An extra copy of the array is not.