Lösungen für Tag 18

2 files changed, 117 insertions, 1 deletions

diff --git a/makefile b/makefile
index 0ce0a6f..26c7f16 100644
--- a/makefile
+++ b/makefile
@@ -16,7 +16,8 @@ all: bin/day01 \
          bin/day14 \
          bin/day15 \
          bin/day16 \
-         bin/day17
+         bin/day17 \
+         bin/day18
 
 bin:
         mkdir $@
diff --git a/src/day18.cpp b/src/day18.cpp
new file mode 100644
index 0000000..3037739
--- /dev/null
+++ b/src/day18.cpp
@@ -0,0 +1,115 @@
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <sstream>
+#include <string>
+#include <vector>
+using namespace std;
+
+using puzzle_t = vector<pair<long, long>>;
+
+puzzle_t
+read_file_part1(string_view filename, long& border_steps)
+{
+        static map<char, pair<int, int>> movement = {
+                { 'U', { 0, -1 } }, // up
+                { 'D', { 0, 1 } },  // down
+                { 'L', { -1, 0 } }, // left
+                { 'R', { 1, 0 } },  // right
+        };
+
+        border_steps = 0;
+
+        fstream  input{ filename };
+        puzzle_t data;
+
+        data.emplace_back(0, 0);
+
+        for ( string line; getline(input, line); ) {
+                char         dir{};
+                long         steps{};
+                stringstream sstrm{ line };
+
+                if ( sstrm >> dir >> steps ) {
+                        data.emplace_back(get<0>(data.back()) + get<0>(movement[dir]) * steps,
+                                          get<1>(data.back()) + get<1>(movement[dir]) * steps);
+
+                        border_steps += steps;
+                }
+        }
+
+        return data;
+}
+
+puzzle_t
+read_file_part2(string_view filename, long& border_steps)
+{
+        static map<char, pair<int, int>> movement = {
+                { '0', { 1, 0 } },  // right
+                { '1', { 0, 1 } },  // down
+                { '2', { -1, 0 } }, // left
+                { '3', { 0, -1 } }, // up
+        };
+
+        border_steps = 0;
+
+        fstream  input{ filename };
+        puzzle_t data;
+
+        data.emplace_back(0, 0);
+
+        for ( string line; getline(input, line); ) {
+                char         dir{};
+                long         steps{};
+                string       hexcode;
+                stringstream sstrm{ line };
+
+                if ( sstrm >> dir >> steps >> hexcode ) {
+                        steps = stol(hexcode.substr(2, 5), nullptr, 16);
+                        dir   = hexcode[7];
+
+                        data.emplace_back(get<0>(data.back()) + get<0>(movement[dir]) * steps,
+                                          get<1>(data.back()) + get<1>(movement[dir]) * steps);
+
+                        border_steps += steps;
+                }
+        }
+
+        return data;
+}
+
+long
+shoelace(const puzzle_t& puzzle, const long border_steps)
+{
+        long area = 0;
+        for ( size_t i = 1; i < puzzle.size(); ++i ) {
+                const auto [x1, y1] = puzzle[i - 1];
+                const auto [x2, y2] = puzzle[i];
+
+                area += (x1 * y2 - y1 * x2);
+        }
+        return (border_steps + area) / 2 + 1;
+}
+
+void
+part1()
+{
+        long border_steps = 0;
+        auto puzzle       = read_file_part1("data/day18.txt", border_steps);
+        cout << shoelace(puzzle, border_steps) << endl;
+}
+
+void
+part2()
+{
+        long border_steps = 0;
+        auto puzzle       = read_file_part2("data/day18.txt", border_steps);
+        cout << shoelace(puzzle, border_steps) << endl;
+}
+
+int
+main()
+{
+        part1();
+        part2();
+}