79 lines
2 KiB
C++
79 lines
2 KiB
C++
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#include <folly/String.h>
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#include <algorithm>
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#include <execution>
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#include <fstream>
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#include <iostream>
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#include <map>
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#include <numeric>
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#include <regex>
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#include <set>
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#include <string_view>
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#include <vector>
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constexpr auto MAX_VOLTAGE_DELTA = 3;
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std::vector<std::string> readInput(const std::string &filename) {
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std::vector<std::string> input;
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std::string line;
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std::ifstream file(filename);
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while (std::getline(file, line)) {
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input.push_back(line);
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}
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return input;
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}
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/**
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* Convert a vector of strings to a vector of numbers
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* @param input The input for the puzzle
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* @return std::vector<int> The puzzle input as numbers
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*/
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std::vector<int> convertInputToNumbers(const std::vector<std::string> &input) {
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std::vector<int> converted;
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converted.reserve(input.size());
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std::transform(input.cbegin(), input.cend(), std::back_inserter(converted), [](const std::string &line) {
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return std::stol(line);
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});
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return converted;
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}
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template <typename Key, typename Value>
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Value getOrDefault(const std::map<Key, Value> &map, Key key, Value defaultValue) {
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try {
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return map.at(key);
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} catch (std::out_of_range) {
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return defaultValue;
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}
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}
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int part1(const std::vector<int> &input) {
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std::map<int, int> differenceCounts;
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std::vector<int> adapters(input);
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int max_voltage = *std::max_element(input.cbegin(), input.cend()) + MAX_VOLTAGE_DELTA;
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adapters.insert(adapters.begin(), 0);
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adapters.insert(adapters.begin(), max_voltage);
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std::sort(adapters.begin(), adapters.end());
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for (auto it = adapters.cbegin() + 1; it != adapters.cend(); it++) {
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auto difference = *it - *(it - 1);
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differenceCounts[difference]++;
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}
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return getOrDefault(differenceCounts, 1, 0) * getOrDefault(differenceCounts, 3, 0);
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}
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int main(int argc, char *argv[]) {
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if (argc != 2) {
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std::cerr << argv[0] << " <input_file>" << std::endl;
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return 1;
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}
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auto input = readInput(argv[1]);
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auto numericInput = convertInputToNumbers(input);
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std::cout << part1(numericInput) << std::endl;
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// std::cout << part2(numbers, part1Answer) << std::endl;
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}
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