81 lines
2.4 KiB
C++
81 lines
2.4 KiB
C++
//
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// Created by Matthew Gretton-Dann on 03/12/2021.
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//
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#include <cassert>
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#include <iostream>
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#include <numeric>
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#include <string>
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#include <vector>
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auto to_num(std::string const& s) -> std::uint64_t
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{
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std::uint64_t result{0};
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for (auto c : s) {
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result <<= 1;
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result |= (c == '1' ? 1 : 0);
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}
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return result;
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}
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auto find_oxygen_rating(std::vector<std::string> const& lines) -> std::string
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{
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std::vector<std::string> data{lines};
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assert(!data.empty());
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std::size_t len{data[1].size()};
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for (std::size_t i{0}; i < len; ++i) {
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auto one_bits{std::accumulate(
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data.begin(), data.end(), std::uint64_t{0},
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[i](std::uint64_t a, std::string const& s) { return a + (s[i] == '1' ? 1 : 0); })};
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char keep{(one_bits * 2 >= data.size()) ? '1' : '0'};
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std::cout << "Size of data = " << data.size() << " Number of one bits = " << one_bits
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<< " keeping " << keep << '\n';
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auto it{std::remove_if(data.begin(), data.end(),
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[keep, i](std::string const& s) { return s[i] != keep; })};
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data.erase(it, data.end());
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if (data.size() <= 1) {
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break;
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}
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}
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assert(data.size() == 1);
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return data[0];
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}
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auto find_co2_rating(std::vector<std::string> const& lines) -> std::string
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{
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std::vector<std::string> data{lines};
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assert(!data.empty());
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std::size_t len{data[1].size()};
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for (std::size_t i{0}; i < len; ++i) {
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auto one_bits{std::accumulate(
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data.begin(), data.end(), std::uint64_t{0},
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[i](std::uint64_t a, std::string const& s) { return a + (s[i] == '1' ? 1 : 0); })};
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char keep{(one_bits * 2 >= data.size()) ? '0' : '1'};
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std::cout << "Size of data = " << data.size() << " Number of one bits = " << one_bits
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<< " keeping " << keep << '\n';
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auto it{std::remove_if(data.begin(), data.end(),
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[keep, i](std::string const& s) { return s[i] != keep; })};
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data.erase(it, data.end());
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if (data.size() <= 1) {
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break;
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}
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}
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assert(data.size() == 1);
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return data[0];
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}
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auto main() -> int
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{
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std::vector<std::string> lines;
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std::string line;
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while (std::getline(std::cin, line)) {
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lines.push_back(line);
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}
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auto oxygen_rating{to_num(find_oxygen_rating(lines))};
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auto co2_rating{to_num(find_co2_rating(lines))};
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std::cout << "Oxygen generator rating * CO2 scrubber rating = " << oxygen_rating << " * "
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<< co2_rating << " = " << oxygen_rating * co2_rating << '\n';
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return 0;
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} |