hard 127 B

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  1. =>((a|b|\p{Nd}){1,2}|aaa|bbbb){1,2}
  2. bab
  3. aaca
  4. aaabbbb
  5. a0b
  6. aa0aaa
  7. b0aaa
  8. =>(\d{1,3}\.){3}\d{1,3}
  9. 1.2.3.4
  10. 1.22.333.44
  11. 1.2.3
  12. 1..2.3