From 1968e4c5b4073351e01321b89a6b3ec937431ea2 Mon Sep 17 00:00:00 2001
From: Bert Peters <bert@bertptrs.nl>
Date: Tue, 17 Dec 2019 18:26:54 +0100
Subject: [PATCH] Really ugly but working day 17 part 2.

---
 2019/src/day17.cpp          | 37 +++++++++++++++++-
 2019/src/day17/route-map.py | 76 +++++++++++++++++++++++++++++++++++++
 2019/src/utils.cpp          |  6 +++
 2019/src/utils.hpp          |  2 +
 4 files changed, 120 insertions(+), 1 deletion(-)
 create mode 100644 2019/src/day17/route-map.py

diff --git a/2019/src/day17.cpp b/2019/src/day17.cpp
index 29dc99a..ebce718 100644
--- a/2019/src/day17.cpp
+++ b/2019/src/day17.cpp
@@ -1,4 +1,6 @@
 #include <iostream>
+#include <string_view>
+#include <cassert>
 #include "days.hpp"
 #include "utils.hpp"
 #include "point.hpp"
@@ -60,5 +62,38 @@ void aoc2019::day17_part1(std::istream &input, std::ostream &output) {
 }
 
 void aoc2019::day17_part2(std::istream &input, std::ostream &output) {
-    output << "Not implemented\n";
+    using namespace std::literals;
+
+    aoc2019::IntCodeComputer computer(input);
+    computer[0] = 2;
+    std::deque<std::int64_t> output_buffer;
+    computer.connectOutput(output_buffer);
+
+    std::array<std::string_view, 3> programs = {
+            "L,6,R,8,L,4,R,8,L,12\n",
+            "L,12,R,10,L,4\n",
+            "L,12,L,6,L,4,L,4\n",
+    };
+
+    auto combined_programs = "A,B,B,C,B,C,B,C,A,A\n"sv;
+
+    computer.sendInputs(combined_programs);
+
+    for (auto program : programs) {
+        computer.sendInputs(program);
+    }
+
+    // Don't give me output.
+    computer.sendInputs("n\n");
+
+    computer.run();
+
+    assert(!output_buffer.empty());
+
+    if (output_buffer.size() == 1) {
+        output << output_buffer.front() << std::endl;
+    } else {
+        std::copy(output_buffer.begin(), output_buffer.end(), std::ostreambuf_iterator<char>(output));
+        output << output_buffer.back() << std::endl;
+    }
 }
diff --git a/2019/src/day17/route-map.py b/2019/src/day17/route-map.py
new file mode 100644
index 0000000..873b2af
--- /dev/null
+++ b/2019/src/day17/route-map.py
@@ -0,0 +1,76 @@
+import fileinput
+import sys
+
+
+def turn_left(direction):
+    x, y = direction
+    return (y, -x)
+
+
+def turn_right(direction):
+    x, y = direction
+    return (-y, x)
+
+
+def add(pos, direction):
+    return tuple(a + b for a, b in zip(pos, direction))
+
+
+def main():
+    chart = [line.strip() for line in fileinput.input()]
+
+    pos = None
+
+    for y, line in enumerate(chart):
+        x = line.find('^')
+        if x >= 0:
+            pos = (x, y)
+            break
+
+    if not pos:
+        sys.exit('starting point not found')
+
+    route = ['L']
+
+    direction = (-1, 0)
+
+    def bounds_check(pos):
+        x, y = pos
+
+        return x >= 0 and y >= 0 and y < len(chart)
+
+    while True:
+        # try to move forward
+        next_pos = add(direction, pos)
+        dist = 0
+
+        while bounds_check(next_pos) and chart[next_pos[1]][next_pos[0]] == '#':
+            dist += 1
+            pos = next_pos
+            next_pos = add(direction, pos)
+
+        if dist:
+            route.append(dist)
+        else:
+            break
+
+        for move, new_dir in zip(('L', 'R'), (turn_left(direction), turn_right(direction))):
+            next_pos = add(pos, new_dir)
+            if bounds_check(next_pos) and chart[next_pos[1]][next_pos[0]] == '#':
+                route.append(move)
+                direction = new_dir
+                break
+
+    printable_route = []
+    for x in route:
+        if x == 'L' or x == 'R':
+            printable_route.append(x)
+        else:
+            printable_route += ['M'] * x
+
+    print(','.join(str(x) for x in route))
+    print(','.join(printable_route))
+
+
+if __name__ == '__main__':
+    main()
diff --git a/2019/src/utils.cpp b/2019/src/utils.cpp
index 1c8f1a8..a037303 100644
--- a/2019/src/utils.cpp
+++ b/2019/src/utils.cpp
@@ -183,3 +183,9 @@ aoc2019::IntCodeComputer::value_t &aoc2019::IntCodeComputer::operator[](std::siz
 const aoc2019::IntCodeComputer::value_t &aoc2019::IntCodeComputer::operator[](std::size_t index) const {
     return program[index];
 }
+
+void aoc2019::IntCodeComputer::sendInputs(std::string_view str) {
+    for (char c : str) {
+        sendInput(c);
+    }
+}
diff --git a/2019/src/utils.hpp b/2019/src/utils.hpp
index 38b3992..c339813 100644
--- a/2019/src/utils.hpp
+++ b/2019/src/utils.hpp
@@ -99,6 +99,8 @@ namespace aoc2019 {
         void connectOutput(std::deque<value_t> &sink);
         void sendInput(value_t input);
 
+        void sendInputs(std::string_view str);
+
         [[nodiscard]] bool isTerminated() const;
 
         [[nodiscard]] const std::deque<value_t> &currentInputs() const;