2017-06

2017/06.cpp

@@ -0,0 +1,88 @@
+#include <algorithm>
+#include <cstdint>
+#include <string>
+#include <iostream>
+#include <tuple>
+#include <array>
+#include <map>
+
+#include <doctest.h>
+
+#include <aocpp/Startup.hpp>
+
+namespace {
+
+template <std::size_t N>
+using Banks = std::array<std::int64_t, N>;
+
+auto Parse(std::istream & in) -> Banks<16> {
+  Banks<16> result;
+  for (auto & x : result) {
+    if (!(in >> x)) {
+      throw std::runtime_error{"bad input"};
+    }
+  }
+  
+  return result;
+}
+
+template <std::size_t N>
+auto Redistribute(Banks<N> & banks) {
+  auto it = std::max_element(banks.begin(), banks.end());
+  auto val = *it;
+  *it++ = 0;
+  for (; val > 0; val--) {
+    if (it == banks.end()) it = banks.begin();
+    (*it++)++;
+  }
+}
+
+template <std::size_t N>
+auto CycleSearch(Banks<N> & banks)
+-> std::pair<std::size_t, std::size_t>
+{
+  std::map<Banks<N>, std::size_t> seen {{banks, 0}};
+  std::size_t n = 0;
+  for(;;) {
+    Redistribute(banks);
+    n++;
+    auto [it, success] = seen.try_emplace(banks, n);
+    if (!success) {
+      return {n, n - it->second};
+    }
+  }
+}
+
+} // namespace
+
+TEST_SUITE("2017-06 examples") {
+  TEST_CASE("example") {
+    Banks<4> banks {0, 2, 7, 0};
+    
+    SUBCASE("single step") {
+      Redistribute(banks);
+      REQUIRE(banks == Banks<4>{2, 4, 1, 2});
+      Redistribute(banks);
+      REQUIRE(banks == Banks<4>{3, 1, 2, 3});
+      Redistribute(banks);
+      REQUIRE(banks == Banks<4>{0, 2, 3, 4});
+      Redistribute(banks);
+      REQUIRE(banks == Banks<4>{1, 3, 4, 1});
+      Redistribute(banks);
+      REQUIRE(banks == Banks<4>{2, 4, 1, 2});
+    }
+
+    SUBCASE("full example") {
+      auto [p1,p2] = CycleSearch(banks);
+      CHECK(p1 == 5);
+      CHECK(p2 == 4);
+    }
+  }
+}
+
+auto main(int argc, char** argv) -> int {
+  auto input = Parse(*aocpp::Startup(argc, argv));
+  auto answer = CycleSearch(input);
+  std::cout << "Part 1: " << answer.first << std::endl;
+  std::cout << "Part 2: " << answer.second << std::endl;
+}

2017/14.cpp

@@ -88,11 +88,13 @@ auto CountComponents(Grid const& grid) -> std::uint16_t {
 
 } // namespace
 
-TEST_CASE("documented example") {
+TEST_SUITE("2017-14 examples") {
+TEST_CASE("flqrgnkx") {
   auto rows = MakeRows("flqrgnkx");
   CHECK(CountBits(rows) == 8108);
   CHECK(CountComponents(rows) == 1242);
 }
+}
 
 auto main(int argc, char** argv) -> int {
   std::string input;

2017/CMakeLists.txt

@@ -1,3 +1,6 @@
+add_executable(2017_06 06.cpp)
+target_link_libraries(2017_06 aocpp)
+
 add_executable(2017_10 10.cpp)
 target_link_libraries(2017_10 aocpp knothash)
 

knothash/src/knothash.cpp

@@ -36,7 +36,7 @@ auto render(std::array<std::uint8_t, 16> const& hash) -> std::string {
   return out.str();
 }
 
-TEST_SUITE("knot hash") {
+TEST_SUITE("knothash library") {
 
 TEST_CASE("reverser") {
   std::array<std::uint8_t, 9> v {0,1,2,3,4,5,6,7,8};
@@ -44,13 +44,13 @@ TEST_CASE("reverser") {
   SUBCASE("more left") {
     std::array<std::uint8_t, 9> expect {1,0,8,7,4,5,6,3,2};
     reverser(v, 7, 6);
-    REQUIRE(v == expect);
+    CHECK(v == expect);
   }
 
   SUBCASE("more right") {
     std::array<std::uint8_t, 9> expect {6,5,2,3,4,1,0,8,7};
     reverser(v, 5, 6);
-    REQUIRE(v == expect);
+    CHECK(v == expect);
   }
 
   SUBCASE("middle") {