84 lines
2.1 KiB
C++
84 lines
2.1 KiB
C++
#include <cstdint>
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#include <iostream>
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#include <sstream>
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#include <tuple>
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#include <vector>
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#include <doctest.h>
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#include <aocpp/Startup.hpp>
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namespace {
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// Parses the numbers and returns them in sorted order
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auto Parse(std::istream & in) -> std::vector<std::int64_t>
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{
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std::vector<std::int64_t> result;
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std::int64_t value;
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while (in >> value) {
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result.push_back(value);
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}
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std::sort(result.begin(), result.end());
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return result;
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}
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auto Part1(std::vector<std::int64_t> const& adapters) -> std::size_t
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{
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std::int64_t prev{0};
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std::size_t ones{0}, threes{1};
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if (adapters.empty()) return 0;
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for (auto const x : adapters) {
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switch (x - prev) {
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case 1: ones++; break;
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case 3: threes++; break;
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}
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prev = x;
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}
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return ones * threes;
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}
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auto Part2(std::vector<std::int64_t> const& adapters) -> std::size_t
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{
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std::size_t n1{1}, n2{0}, n3{0};
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std::int64_t prev{0};
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for (auto const x : adapters) {
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switch(x - prev) {
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case 1: std::tie(n1,n2,n3) = std::make_tuple(n1+n2+n3, n1, n2); break;
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case 2: std::tie(n1,n2,n3) = std::make_tuple(n1+n2, 0, n1); break;
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case 3: std::tie(n1,n2,n3) = std::make_tuple(n1, 0, 0); break;
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default: std::tie(n1,n2,n3) = std::make_tuple(0 , 0, 0); break;
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}
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prev = x;
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}
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return n1;
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}
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} // namespace
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TEST_SUITE("documented examples") {
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TEST_CASE("part 1") {
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std::istringstream in {"16 10 15 5 1 11 7 19 6 12 4"};
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REQUIRE(Part1(Parse(in)) == 7*5);
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in = std::istringstream{"28 33 18 42 31 14 46 20 48 47 24 23 49 45 19 38 39 11 1 32 25 35 8 17 7 9 4 2 34 10 3 "};
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REQUIRE(Part1(Parse(in)) == 22*10);
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}
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TEST_CASE("part 2") {
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std::istringstream in {"16 10 15 5 1 11 7 19 6 12 4"};
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REQUIRE(8 == Part2(Parse(in)));
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in = std::istringstream{"28 33 18 42 31 14 46 20 48 47 24 23 49 45 19 38 39 11 1 32 25 35 8 17 7 9 4 2 34 10 3 "};
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REQUIRE(19208 == Part2(Parse(in)));
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}
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}
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auto Main(std::istream & in, std::ostream & out) -> void
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{
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auto const adapters {Parse(in)};
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out << "Part 1: " << Part1(adapters) << std::endl;
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out << "Part 2: " << Part2(adapters) << std::endl;
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}
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