How to find all words with regular expression in Notepad++?

Question

Regular Expressions

there is a large list of words it is necessary to find by 3 letters all the words where there are these letters set the letters UHY
wrote a regular expression
[x|y|y]\w{0,}?[x|y|y]\w{0,}[x |y|d]
notepd finds all words containing these letters. BUT there are more of these words than you need
alcuronium chloride found all the letters,
but in this list there are words where there is no one letter
baUHHoden
the letter X repeated twice

How to make sure that the letter does not repeat twice

Answer 1

(?i:у()|х()|й()|\w)++\1\2\3
https://regex101.com/r/VIsgfS/1
\b(?=\w*?у)(?=\w*?х)(?=\w*?й)\w+
https://regex101.com/r/VIsgfS/3