28 lines
1 KiB
Nim
28 lines
1 KiB
Nim
import streams, strutils, re
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type PasswordPolicy = tuple[min: int, max: int, keyChar: char]
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let parsePasswordLineRe = re"^(\d+)-(\d+) (.): (.*)$"
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proc parsePasswordLine(str: string): (PasswordPolicy, string) =
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var matches: array[4, string]
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if match(str, parsePasswordLineRe, matches):
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return ((min: parseInt(matches[0]), max: parseInt(matches[1]), keyChar: matches[2][0]), matches[3])
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iterator asPasswordPolicies(s: Stream): (PasswordPolicy, string) =
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for line in s.lines(): yield parsePasswordLine line
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proc isValidPassword(str: string, pp: PasswordPolicy): bool =
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let count = str.count pp.keyChar
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(pp.min <= count) and (count <= pp.max)
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proc isValidPasswordPart2(str: string, pp: PasswordPolicy): bool =
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(str[pp.min - 1] == pp.keyChar) xor (pp.keyChar == str[pp.max - 1])
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proc part1*(s: Stream): int =
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for (pp, pw) in s.asPasswordPolicies:
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if isValidPassword(pw, pp): inc result
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proc part2*(s: Stream): int =
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for (pp, pw) in s.asPasswordPolicies:
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if isValidPasswordPart2(pw, pp): inc result
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