feat: solve day 4 puzzle 1

README.md

@@ -8,10 +8,10 @@ This project can also be run using the amazing [CraftOS-PC emulator](https://git
 ## Progress
 
 <!-- calendar-start -->
-#### Stars: 6/24
+#### Stars: 7/24
 
 |Mon|Tue|Wed|Thu|Fri|Sat|Sun|
 |:-:|:-:|:-:|:-:|:-:|:-:|:-:|
-|1<br>:star::star:|2<br>:star::star:|3<br>:star::star:|4<br>|5<br>|6<br>|7<br>|
+|1<br>:star::star:|2<br>:star::star:|3<br>:star::star:|4<br>:star:|5<br>|6<br>|7<br>|
 |8<br>|9<br>|10<br>|11<br>|12<br>|||
 <!-- calendar-end -->

res/examples/day04.txt

@@ -0,0 +1,10 @@
+..@@.@@@@.
+@@@.@.@.@@
+@@@@@.@.@@
+@.@@@@..@.
+@@.@@@@.@@
+.@@@@@@@.@
+.@.@.@.@@@
+@.@@@.@@@@
+.@@@@@@@@.
+@.@.@@@.@.

res/stats.json

@@ -12,7 +12,7 @@
         "puzzle2": true
     },
     "day04": {
-        "puzzle1": false,
+        "puzzle1": true,
         "puzzle2": false
     },
     "day05": {

src/day04/puzzle1.lua

@@ -0,0 +1,44 @@
+local utils = require "utils"
+
+local puzzle1 = {}
+
+function puzzle1.inGrid(x, y, w, h)
+    return 1 <= x and x <= w and 1 <= y and y <= h
+end
+
+function puzzle1.isAccessible(lines, w, h, x, y)
+    local neighbors = 0
+    for dy=-1, 1 do
+        for dx=-1, 1 do
+            if dx ~=0 or dy ~= 0 then
+                local x2 = x + dx
+                local y2 = y + dy
+                if puzzle1.inGrid(x2, y2, w, h) then
+                    if lines[y2]:sub(x2, x2) == "@" then
+                        neighbors = neighbors + 1
+                    end
+                end
+            end
+        end
+    end
+    return neighbors < 4
+end
+
+function puzzle1.solve(input)
+    local lines = utils.splitLines(input)
+    local accessible = 0
+
+    local h = #lines
+    local w = #lines[1]
+
+    for y, line in ipairs(lines) do
+        for x=1, #line do
+            if line:sub(x, x) == "@" and puzzle1.isAccessible(lines, w, h, x, y) then
+                accessible = accessible + 1
+            end
+        end
+    end
+    return accessible
+end
+
+return puzzle1

src/day04/puzzle2.lua

@@ -0,0 +1,7 @@
+local puzzle2 = {}
+
+function puzzle2.solve(input)
+    return 0
+end
+
+return puzzle2