Unique chars with shift and operators : don't understand this code?

The code assumes that str is made of lower case letters and returns true if there are no repeating letters. It works like this.

Str. CharAt(i) - 'a' returns, more or less, the "letter in the alphabet": if str. CharAt(i) is 'a', this is 0, if it's 'b', val is 1, if it's z, val is 25, and so on.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.