aoc2020/day2/part2/main.d

37 lines
906 B
D
Raw Permalink Normal View History

2020-12-02 10:46:41 +01:00
module day2.part2.main;
import std;
void main()
{
const passwords = slurp!(size_t, size_t, char, string)("input", "%s-%s %s: %s");
passwords.findNumberOfValidPasswords.writeln;
}
alias PasswordWithPolicy = Tuple!(size_t, size_t, char, string);
ulong findNumberOfValidPasswords(const PasswordWithPolicy[] passwords)
{
2020-12-02 11:59:13 +01:00
return passwords.filter!isPasswordValid.count;
2020-12-02 10:46:41 +01:00
}
bool isPasswordValid(const PasswordWithPolicy password)
{
immutable pos1 = password[0] - 1;
immutable pos2 = password[1] - 1;
immutable character = password[2];
immutable actualPassword = password[3];
return (actualPassword[pos1] == character) != (actualPassword[pos2] == character);
}
unittest
{
immutable input = [
tuple(1UL, 3UL, 'a', "abcde"),
tuple(1UL, 3UL, 'b', "cdefg"),
tuple(2UL, 9UL, 'c', "ccccccccc")
];
assert(input.findNumberOfValidPasswords == 1);
}