89 lines
2.0 KiB
C++
89 lines
2.0 KiB
C++
//
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// Created by Matthew Gretton-Dann on 01/12/2022.
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//
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#include <algorithm>
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#include <cstdlib>
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#include <iomanip>
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#include <iostream>
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#include <list>
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#include <map>
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#include <regex>
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#include <utility>
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using UInt = std::uint64_t;
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using Int = std::int64_t;
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using State = std::list<UInt>;
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using Players = std::vector<UInt>;
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template<typename iterator>
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auto move(iterator begin, iterator end, iterator current, Int count)
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{
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while (count > 0) {
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if (current == end) {
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current = begin;
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}
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++current;
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--count;
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}
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while (count < 0) {
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if (current == begin) {
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current = end;
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}
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--current;
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++count;
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}
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if (current == end) {
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current = begin;
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}
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return current;
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}
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auto main() -> int
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{
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std::string line;
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std::regex const re{"(\\d+) players; last marble is worth (\\d+) points"};
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// Read data
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if (!std::getline(std::cin, line)) {
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std::cerr << "Unable to read line.\n";
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return EXIT_FAILURE;
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}
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std::smatch m;
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if (!std::regex_match(line, m, re)) {
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std::cerr << "Unable to interpret: " << line << "\n";
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return EXIT_FAILURE;
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}
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UInt const player_count{std::stoull(m.str(1))};
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UInt const last_marble{std::stoull(m.str(2)) * 100};
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Players players(player_count, 0);
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State game;
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game.push_back(0);
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auto current_pos{game.begin()};
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UInt player{0};
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for (UInt marble{1}; marble <= last_marble; ++marble) {
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if (marble % 23 == 0) {
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current_pos = move(game.begin(), game.end(), current_pos, -7);
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players[player] += marble + *current_pos;
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current_pos = game.erase(current_pos);
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if (current_pos == game.end()) {
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current_pos = game.begin();
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}
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}
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else {
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current_pos = move(game.begin(), game.end(), current_pos, 2);
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current_pos = game.insert(current_pos, marble);
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}
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player = (player + 1) % player_count;
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}
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auto max_elt{std::max_element(players.begin(), players.end())};
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std::cout << "high score is: " << *max_elt << "\n";
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return EXIT_SUCCESS;
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}
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