My Answer in Regex Golf

Warm Up

Answer： foo Point(3)

Anchors

Answer: k$ Point(2)

It never ends $ not allowed

Answer: fu Point(4) 或者 u

Ranges

Answer:[a-f][a-f][a-f][a-f] Point(20)

Backrefs

Answer: (...).*1 Point(9)

Abba

Answer: ^(?!.*(.)(.)21) Point(17)

A man, a plan

Answer: ^(.)(.).*21$

Four

Answer: ([aioe]).1.1.1

Order

Answer: ^[1][c-o][c-t][e-t][i-z][n-z]?$

Prime

Answer: ^(?!(..+)1+$)

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1. a-m ↩︎