Algorithms in C$++$:

$1.$ Objective

Your goal is to write a program that determines if a string has all unique lowercase letters.

$2.$ Problem

The string will be read as a command line argument to the program. The program will then check if thestring has all lowercase letters. If it does not, the program will display an error message and exit. Otherwise, the program will determine whether or not the string has all unique lowercase characters.

Case $1$: No input arguments

Print usage message.

$ $./$unique

Usage: $./$unique

Case $2$: Too many input arguments

Print usage message.

$ $./$unique too many words

Usage: $./$unique

Case $3$: Bad input

$ $./$unique HI

Error: String must contain only lowercase letters.

Case $4$: Bad input

$ $./$unique $1234567890$

Error: String must contain only lowercase letters.

Case $5$: Unique

$ $./$unique abcdefghijklmnopqrstuvwxyz

All letters are unique.

Case $6$: Duplicates

$ $./$unique longstring

Duplicate letters found.

$3.$ Hint

When a letter is seen, check if the corresponding bit is equal to $1.$ If it is$,$ the letter has already been seen and must be a duplicate. Otherwise, change the corresponding bit from $0$ to $1.$