94 lines
2.0 KiB
C++
94 lines
2.0 KiB
C++
#include <cstdint> // int64_t
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#include <functional> // plus
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#include <iostream> // istream
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#include <iterator> // istream_iterator
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#include <numeric> // transform_reduce
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#include <sstream> // istringstream
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#include <string> // string
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#include <tuple> // pair, make_pair
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#include <doctest.h>
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#include <aocpp/DivMod.hpp>
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#include <aocpp/Startup.hpp>
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namespace {
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using aocpp::DivMod;
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using It = std::istream_iterator<std::string>;
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template <typename T>
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auto FromInt(T x) -> std::string
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{
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std::string output;
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char const digits[] {"=-012"};
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while (x != 0) {
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auto [x_, i] = DivMod<T>(x + 2, 5); // plain % and / are insufficient for negatives
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x = x_;
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output.push_back(digits[i]);
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}
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std::reverse(output.begin(), output.end());
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return output;
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}
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template <typename T>
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auto ToInt(std::string const& str) -> T
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{
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T acc {0};
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for (char c : str) {
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acc *= 5;
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switch (c) {
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case '2': acc += 2; break;
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case '1': acc += 1; break;
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case '0': break;
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case '-': acc -= 1; break;
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case '=': acc -= 2; break;
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}
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}
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return acc;
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}
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auto Solve(std::istream & in) -> std::string
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{
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return FromInt(std::transform_reduce(It{in}, It{}, std::int64_t{}, std::plus(), ToInt<std::int64_t>));
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}
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} // namespace
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TEST_SUITE("2022-25 examples") {
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TEST_CASE("example") {
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std::istringstream in {
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"1=-0-2\n"
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"12111\n"
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"2=0=\n"
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"21\n"
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"2=01\n"
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"111\n"
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"20012\n"
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"112\n"
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"1=-1=\n"
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"1-12\n"
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"12\n"
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"1=\n"
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"122\n"
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};
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CHECK(Solve(in) == "2=-1=0");
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}
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// The example input doesn't test out any negative numbers
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TEST_CASE("Negative numbers") {
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CHECK(ToInt<int>("-") == -1);
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CHECK(ToInt<int>("=") == -2);
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CHECK(ToInt<int>("-=") == -7);
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CHECK(ToInt<int>("=-") == -11);
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CHECK(FromInt(-1) == "-");
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CHECK(FromInt(-2) == "=");
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CHECK(FromInt(-7) == "-=");
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CHECK(FromInt(-11) == "=-");
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}
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}
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auto Main(std::istream & in) -> void
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{
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std::cout << "Part 1: " << Solve(in) << std::endl;
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}
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