nrinaudo / nice-strings

Solution to a fun challenge I was given

Naughty and Nice Strings

Challenge:

We need help figuring out which strings in a text file are naughty or nice. All of the strings are made up only of the lower-case characters 'a' to 'z'. A nice string is one with all of the following properties:

• It contains at least three vowels (aeiou only), like aei, xazegov, or aeiouaeiouaeiou.
• It contains at least one letter that appears twice in a row, like xx, abcdde (dd), or aabbccdd (aa, bb, cc, or dd).
• It does not contain the strings ab, cd, pq, or xy, even if they are part of one of the other requirements.

Any string which is not nice is called a naughty string.

For example:

• ugknbfddgicrmopn is nice because it has at least three vowels (u...i...o...), a double letter (...dd...), and none of the disallowed substrings.
• aaa is nice because it has at least three vowels and a double letter, even though the letters used by different rules overlap.
• jchzalrnumimnmhp is naughty because it has no double letter.
• haegwjzuvuyypxyu is naughty because it contains the string xy.
• dvszwmarrgswjxmb is naughty because it contains only one vowel.

Given an input file with one string per line, how many of those strings are nice?

Checking the implementation

A set of test cases is included in /src/main/resources/sample-input.txt. This should yield 255 matches in a total of 1.000 strings (one per line).