This doesn't handle Yellow result correctly. Specifically, if there is a repeated letter in the guess but that letter appears once in the actual word, then the second occurrence will get a Black instead of a Yellow.
In other words, a Yellow result doesn't just mean that letter occurs somewhere. A Black also doesn't mean the letter occurs nowhere.
In other words, a Yellow result doesn't just mean that letter occurs somewhere. A Black also doesn't mean the letter occurs nowhere.