103 lines
3.0 KiB
C++
103 lines
3.0 KiB
C++
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#include <algorithm>
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#include <deque>
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#include <fstream>
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#include <iostream>
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#include <sstream>
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#include <unordered_map>
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#include <unordered_set>
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#include <vector>
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using Rules =
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std::unordered_map<std::string, std::pair<std::string, std::string>>;
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using Growth =
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std::unordered_map<std::string, std::unordered_map<char, uint64_t>>;
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std::pair<std::string, Rules> getRules(const std::string &file_name) {
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Rules rules{};
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std::string input{};
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std::ifstream file(file_name);
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std::string str;
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bool isFold = false;
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std::getline(file, input);
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std::getline(file, str);
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while (std::getline(file, str)) {
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auto in = str.substr(0, 2);
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auto mid = str.substr(6, 1);
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rules[in] = { in[0] + mid, mid + in[1] };
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}
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return { input, rules };
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}
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uint64_t calculateDifferenceAfterRounds(const Rules &rules,
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const std::string &text, int rounds) {
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std::unordered_map<std::string, uint64_t> pair_count{};
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for (auto &rule : rules) {
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pair_count[rule.first] = 0;
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}
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for (int i = 0; i < text.size() - 1; i++) {
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pair_count[text.substr(i, 2)] += 1;
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}
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for (int i = 0; i < rounds; i++) {
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std::unordered_map<std::string, uint64_t> new_pair_count{};
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for (auto &rule : rules) {
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new_pair_count[rule.first] = 0;
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}
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for (auto &pair : pair_count) {
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auto new_pairs = rules.at(pair.first);
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new_pair_count[new_pairs.first] += pair.second;
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new_pair_count[new_pairs.second] += pair.second;
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}
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pair_count = new_pair_count;
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}
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std::unordered_map<char, uint64_t> char_count{};
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for (auto &pair : pair_count) {
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char c = pair.first[0];
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if (char_count.find(c) == char_count.end()) {
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char_count[c] = pair.second;
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} else {
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char_count[c] += pair.second;
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}
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}
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char_count[text.back()] += 1;
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uint64_t min = -1, max = 0;
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for (auto &c : char_count) {
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if (c.second < min) {
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min = c.second;
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}
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if (c.second > max) {
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max = c.second;
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}
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}
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return max - min;
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}
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uint64_t part1(Rules &rules, const std::string &text) {
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return calculateDifferenceAfterRounds(rules, text, 10);
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}
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uint64_t part2(Rules &rules, const std::string &text) {
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return calculateDifferenceAfterRounds(rules, text, 40);
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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 << "You must provide input file!" << std::endl;
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return 1;
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}
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auto text_and_rules = getRules(argv[1]);
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auto &text = text_and_rules.first;
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auto &rules = text_and_rules.second;
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std::cout << "The difference between the most common and least common "
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"letters after 10 rounds is \033[91;1m"
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<< part1(rules, text) << "\033[0m." << std::endl;
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std::cout << "The difference between the most common and least common "
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"letters after 40 rounds is \033[91;1m"
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<< part2(rules, text) << "\033[0m." << std::endl;
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return 0;
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}
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