initial commit, day 10

10.cpp

@@ -0,0 +1,129 @@
+#include <iostream>
+#include <array>
+#include <cstdint>
+#include <fstream>
+#include <iterator>
+#include <unordered_set>
+
+using map_t = std::array<std::array<uint8_t, 55>, 54>;
+
+struct Point
+{
+    int16_t Row;
+    int16_t Col;
+};
+
+using sols_t = std::unordered_set<uint32_t>;
+
+void load_map(map_t& map, const char* filepath)
+{
+    std::fstream in(filepath);
+    std::istreambuf_iterator<char> iter(in);
+    // std::istream_iterator<char> end;
+    for (auto& row : map)
+    {
+        for (auto& cell : row)
+        {
+            cell = *(iter++);
+        }
+    }
+}
+
+void branch(const map_t& map, sols_t& terminals, char height, Point pos)
+{
+    if (height == '9')
+        terminals.emplace((pos.Row << 16) + pos.Col);
+    else
+    {
+        if (pos.Row > 0 && map[pos.Row-1][pos.Col] == height+1)
+        {
+            branch(map, terminals, height+1, {pos.Row-1, pos.Col});
+        }
+        if (pos.Row < map.size()-1 && map[pos.Row+1][pos.Col] == height+1)
+        {
+            branch(map, terminals, height+1, {pos.Row+1, pos.Col});
+        }
+        if (pos.Col > 0 && map[pos.Row][pos.Col-1] == height+1)
+        {
+            branch(map, terminals, height+1, {pos.Row, pos.Col-1});
+        }
+        if (pos.Col < map[0].size()-2 && map[pos.Row][pos.Col+1] == height+1)
+        {
+            branch(map, terminals, height+1, {pos.Row, pos.Col+1});
+        }
+    }
+}
+
+int64_t branch2(const map_t& map, char height, Point pos)
+{
+    if (height == '9')
+        return 1;
+    else
+    {
+        int64_t total = 0;
+        if (pos.Row > 0 && map[pos.Row-1][pos.Col] == height+1)
+        {
+            total += branch2(map, height+1, {pos.Row-1, pos.Col});
+        }
+        if (pos.Row < map.size()-1 && map[pos.Row+1][pos.Col] == height+1)
+        {
+            total += branch2(map, height+1, {pos.Row+1, pos.Col});
+        }
+        if (pos.Col > 0 && map[pos.Row][pos.Col-1] == height+1)
+        {
+            total += branch2(map, height+1, {pos.Row, pos.Col-1});
+        }
+        if (pos.Col < map[0].size()-2 && map[pos.Row][pos.Col+1] == height+1)
+        {
+            total += branch2(map, height+1, {pos.Row, pos.Col+1});
+        }
+        return total;
+    }
+}
+
+void main1(const map_t& map)
+{
+    int total = 0;
+    // for (const auto& row : map)
+    //     for (const auto& cell : row)
+    //         std::cout << cell;
+    // std::cout << std::endl;
+    for (int16_t r = 0; r < map.size(); r++)
+    {
+        for (int16_t c = 0; c < map[r].size()-1; c++)
+        {
+            if (map[r][c] == '0')
+            {
+                sols_t terminals;
+                branch(map, terminals, '0', {r, c});
+                total += terminals.size();
+            }
+        }
+    }
+    std::cout << "Part1 " << total << std::endl;
+}
+
+void main2(const map_t& map)
+{
+    int64_t total = 0;
+    for (int16_t r = 0; r < map.size(); r++)
+    {
+        for (int16_t c = 0; c < map[r].size()-1; c++)
+        {
+            if (map[r][c] == '0')
+            {
+                total += branch2(map, '0', {r, c});
+            }
+        }
+    }
+    std::cout << "Part2 " << total << std::endl;
+}
+
+int main()
+{
+    map_t map;
+    load_map(map, "10.txt");
+    main1(map);
+    main2(map);
+    return 0;
+}