From c3b3de5416c34af7473abde3628326cc87ad4954 Mon Sep 17 00:00:00 2001
From: Eric Mertens <emertens@gmail.com>
Date: Sat, 12 Nov 2022 21:22:07 -0800
Subject: [PATCH] 19

---
 2019/19.cpp                         | 52 +++++++++++++++++++++++++++++
 2019/CMakeLists.txt                 |  3 ++
 intcode/include/intcode/Machine.hpp |  1 +
 intcode/src/Machine.cpp             |  6 ++++
 4 files changed, 62 insertions(+)
 create mode 100644 2019/19.cpp

diff --git a/2019/19.cpp b/2019/19.cpp
new file mode 100644
index 0000000..63abf22
--- /dev/null
+++ b/2019/19.cpp
@@ -0,0 +1,52 @@
+#include <iostream>
+
+#include <aocpp/Coord.hpp>
+#include <aocpp/Startup.hpp>
+#include <intcode/intcode.hpp>
+
+using namespace aocpp;
+using namespace intcode;
+
+namespace {
+
+class Scanner {
+  Machine machine_;
+
+public:
+  Scanner(Machine machine) : machine_{std::move(machine)} {}
+
+  auto operator()(ValueType x, ValueType y) const -> bool {
+    Machine m {machine_};
+    StepInput(m, x);
+    StepInput(m, y);
+    return StepOutput(m);
+  }
+};
+
+auto Part1(Scanner const& scanner) {
+  std::int64_t count {};
+  for (std::int64_t y = 0; y < 50; y++) {
+    for (std::int64_t x = 0; x < 50; x++) {
+      if (scanner(x, y)) {
+        count++;
+      }
+    }
+  }
+  return count;
+}
+
+auto Part2(Scanner const& scanner) {
+  ValueType x = 0;
+  for(ValueType y = 99;; y++){
+    for (; !scanner(x, y); x++);
+    if (scanner(x+99,y-99)) { return 10000 * x + y-99; }
+  }
+}
+
+} // namespace
+
+auto main(int argc, char** argv) -> int {
+  auto scanner = Scanner{Machine{ParseStream(aocpp::Startup(argc, argv))}};
+  std::cout << "Part 1: " << Part1(scanner) << std::endl;
+  std::cout << "Part 2: " << Part2(scanner) << std::endl;
+}
diff --git a/2019/CMakeLists.txt b/2019/CMakeLists.txt
index 95705e6..7ad5c2d 100644
--- a/2019/CMakeLists.txt
+++ b/2019/CMakeLists.txt
@@ -49,6 +49,9 @@ target_link_libraries(17 aocpp intcode)
 add_executable(18 18.cpp)
 target_link_libraries(18 aocpp)
 
+add_executable(19 19.cpp)
+target_link_libraries(19 aocpp intcode)
+
 add_executable(20 20.cpp)
 target_link_libraries(20 aocpp)
 
diff --git a/intcode/include/intcode/Machine.hpp b/intcode/include/intcode/Machine.hpp
index 7cd100a..86e4f2f 100644
--- a/intcode/include/intcode/Machine.hpp
+++ b/intcode/include/intcode/Machine.hpp
@@ -27,6 +27,7 @@ public:
   /// @param address
   /// @return reference to memory at given address
   auto At(std::size_t address) -> ValueType &;
+  auto At(std::size_t address) const -> ValueType;
 
   /// Access memory at address relative to base pointer
   /// @param offset from base pointer
diff --git a/intcode/src/Machine.cpp b/intcode/src/Machine.cpp
index 33cc276..9fc0a9c 100644
--- a/intcode/src/Machine.cpp
+++ b/intcode/src/Machine.cpp
@@ -11,6 +11,12 @@ auto Machine::At(std::size_t const i) -> ValueType & {
   return i < rom_.size() ? rom_[i] : ram_[i];
 }
 
+auto Machine::At(std::size_t const i) const -> ValueType {
+  if (i < rom_.size()) return rom_[i];
+  if (auto it = ram_.find(i); it != ram_.end()) { return it->second; }
+  return 0;
+}
+
 auto Machine::Rel(std::size_t const i) -> ValueType & {
   return At(base_ + i);
 }