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Added day 10, part 2

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Chris Josten 2020-12-10 10:51:21 +01:00
parent f728b02ad6
commit ddbdb8e69d
Signed by: chris
GPG key ID: 1795A594046530AB
1 changed files with 25 additions and 1 deletions
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26
source/day10.d
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@ -12,7 +12,8 @@ Variant run(int part, File input, bool bigboy, string[] args) {
auto sortedNumbers = numbers.sort;
Variant result = parts!size_t(part,
() => part1(sortedNumbers));
() => part1(sortedNumbers),
() => part2(sortedNumbers));
return result;
}
@ -36,3 +37,26 @@ unittest {
numbers ~= [0u];
assert(part1(numbers.sort) == 220);
}
size_t part2(T)(SortedRange!(T[]) numbers) {
auto numbers2 = merge(numbers, [numbers[$ - 1] + 3]).array;
size_t[] options;
options.length = numbers2[$ -1] + 1;
fill(options, 0);
options[0] = 1;
foreach(int number; numbers2) {
foreach(int diff; 1..4) {
if ((number - diff) >= 0) options[number] += options[number - diff];
}
}
size_t result = options[$ - 1];
return result;
}
unittest {
uint[] numbers = [28, 33, 18, 42, 31, 14, 46, 20, 48, 47, 24, 23, 49, 45, 19, 38, 39, 11, 1, 32,
25, 35, 8, 17, 7, 9, 4, 2, 34, 10, 3];
numbers ~= [0u];
assert(part2(numbers.sort) == 19208);
}