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Implement day 14 part 2.

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Bert Peters
2019-12-14 14:43:20 +01:00
parent 5306e7aa94
commit 535d37ca42
7 changed files with 30 additions and 4 deletions
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28
2019/src/day14.cpp
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@@ -99,16 +99,36 @@ namespace {
return ore_needed;
}
std::int64_t ore_to_fuel(const std::map<reqlist_t, reqlist_t> &recipes, std::int64_t amount = 1) {
auto inverted = element_creators(recipes);
std::unordered_map<std::string, std::int64_t> stock;
return ore_required("FUEL", amount, stock, recipes, inverted);
}
}
void aoc2019::day14_part1(std::istream &input, std::ostream &output) {
auto recipes = read_recipes(input);
auto inverted = element_creators(recipes);
std::unordered_map<std::string, std::int64_t> stock;
output << ore_required("FUEL", 1, stock, recipes, inverted) << std::endl;
output << ore_to_fuel(recipes) << std::endl;
}
void aoc2019::day14_part2(std::istream &input, std::ostream &output) {
output << "Not implemented\n";
auto recipes = read_recipes(input);
constexpr std::int64_t ore_stock = 1000000000000;
std::int64_t min = 1, max = ore_stock + 1; // assumption: 1 ore produces < 1 fuel.
while (max - min > 1) {
auto cur = (max + min) / 2;
if (ore_to_fuel(recipes, cur) < ore_stock) {
min = cur;
} else {
max = cur - 1;
}
}
output << (max + min) / 2 << std::endl;
}