82 lines
2.4 KiB
C++
82 lines
2.4 KiB
C++
#include <string>
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#include <sstream>
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#include <chrono>
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#include <iostream>
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#include <vector>
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#include <unordered_map>
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using std::cout, std::endl;
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constexpr const char content[] = {
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#embed "input.txt"
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};
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uint64_t num_stones(std::vector<uint64_t>& numbers, uint64_t blinks) {
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std::unordered_map<uint64_t, uint64_t> nums = {};
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for(auto num : numbers) {
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nums[num] = 1;
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}
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for(int i{0}; i < blinks; i++) {
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std::unordered_map<uint64_t, uint64_t> new_nums = {};
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for(auto &[num, count] : nums) {
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if(num == 0) {
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new_nums[1] += count;
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} else if (std::to_string(num).length() % 2 == 0) {
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std::string num_str = std::to_string(num);
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uint64_t left = std::stoi(num_str.substr(0, num_str.length() / 2));
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uint64_t right = std::stoi(num_str.substr(num_str.length() / 2));
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new_nums[left] += count;
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new_nums[right] += count;
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} else {
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uint64_t new_num = num * 2024;
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new_nums[new_num] += count;
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}
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}
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nums = new_nums;
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}
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uint64_t total = 0;
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for(auto &[_, count] : nums) {
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total += count;
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}
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return total;
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}
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uint64_t part_1() {
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std::istringstream input_stream(content);
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std::string line;
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std::vector<uint64_t> numbers = {};
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uint64_t curr_num;
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while(input_stream >> curr_num) {
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numbers.emplace_back(curr_num);
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}
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return num_stones(numbers, 25);
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}
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uint64_t part_2() {
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std::istringstream input_stream(content);
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std::string line;
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std::vector<uint64_t> numbers = {};
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uint64_t curr_num;
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while(input_stream >> curr_num) {
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numbers.emplace_back(curr_num);
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}
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return num_stones(numbers, 75);
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}
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int main() {
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std::chrono::steady_clock::time_point begin = std::chrono::steady_clock::now();
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auto p1_val = part_1();
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std::chrono::steady_clock::time_point middle = std::chrono::steady_clock::now();
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auto p2_val = part_2();
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std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
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cout << "Part 1: " << p1_val << " (" << std::chrono::duration_cast<std::chrono::microseconds>(middle - begin).count() << "µs)" << endl;
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cout << "Part 2: " << p2_val << " (" << std::chrono::duration_cast<std::chrono::microseconds>(end - middle).count() << "µs)" << endl;
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return 0;
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}
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