feat: solve day 8 puzzle 2

README.md

@@ -8,10 +8,10 @@ This project can also be run using the amazing [CraftOS-PC emulator](https://git
 ## Progress
 
 <!-- calendar-start -->
-#### Stars: 14/24
+#### Stars: 16/24
 
 |Mon|Tue|Wed|Thu|Fri|Sat|Sun|
 |:-:|:-:|:-:|:-:|:-:|:-:|:-:|
 |1<br>:star::star:|2<br>:star::star:|3<br>:star::star:|4<br>:star::star:|5<br>:star::star:|6<br>:star::star:|7<br>:star::star:|
-|8<br>|9<br>|10<br>|11<br>|12<br>|||
+|8<br>:star::star:|9<br>|10<br>|11<br>|12<br>|||
 <!-- calendar-end -->

res/examples/day08.txt

@@ -0,0 +1,20 @@
+162,817,812
+57,618,57
+906,360,560
+592,479,940
+352,342,300
+466,668,158
+542,29,236
+431,825,988
+739,650,466
+52,470,668
+216,146,977
+819,987,18
+117,168,530
+805,96,715
+346,949,466
+970,615,88
+941,993,340
+862,61,35
+984,92,344
+425,690,689

res/stats.json

@@ -28,8 +28,8 @@
         "puzzle2": true
     },
     "day08": {
-        "puzzle1": false,
+        "puzzle1": true,
-        "puzzle2": false
+        "puzzle2": true
     },
     "day09": {
         "puzzle1": false,

src/day08/puzzle1.lua

@@ -0,0 +1,82 @@
+local utils = require "utils"
+local puzzle1 = {}
+
+function puzzle1.dist(box1, box2)
+    return math.sqrt(
+        (box2.x - box1.x) ^ 2 +
+        (box2.y - box1.y) ^ 2 +
+        (box2.z - box1.z) ^ 2
+    )
+end
+
+function puzzle1.pretty(box)
+    return ("%d,%d,%d"):format(box.x, box.y, box.z)
+end
+
+function puzzle1.solve(input)
+    local boxes = {}
+
+    local lines = utils.splitLines(input)
+
+    for i, line in ipairs(lines) do
+        local x, y, z = line:match("(%d+),(%d+),(%d+)")
+        table.insert(boxes, {x=x, y=y, z=z, i=i, circuit=i})
+    end
+
+    local dists = {}
+    local circuits = {}
+
+    for i, box1 in ipairs(boxes) do
+        circuits[i] = i
+        for j=i+1, #boxes do
+            local box2 = boxes[j]
+            table.insert(dists, {
+                i=i,
+                j=j,
+                dist=puzzle1.dist(box1, box2)
+            })
+        end
+    end
+
+    table.sort(dists, function (a, b)
+        return a.dist < b.dist
+    end)
+
+    local N = 1000
+    if #boxes < 100 then
+        N = 10
+    end
+
+    for i, d in ipairs(dists) do
+        if i > N then
+            break
+        end
+        local circ1 = circuits[d.i]
+        local circ2 = circuits[d.j]
+
+        for k, v in pairs(circuits) do
+            if v == circ2 then
+                circuits[k] = circ1
+            end
+        end
+    end
+
+    local circuitSizes = {}
+
+    for _, c in pairs(circuits) do
+        circuitSizes[c] = (circuitSizes[c] or 0) + 1
+    end
+
+    local sizes = {}
+
+    for _, s in pairs(circuitSizes) do
+        table.insert(sizes, s)
+    end
+
+    table.sort(sizes)
+    local n = #sizes
+
+    return sizes[n] * sizes[n - 1] * sizes[n - 2]
+end
+
+return puzzle1

src/day08/puzzle2.lua

@@ -0,0 +1,52 @@
+local utils = require "utils"
+local puzzle1 = require(SRC_PATH .. "/day08/puzzle1")
+local puzzle2 = {}
+
+function puzzle2.solve(input)
+    local boxes = {}
+
+    local lines = utils.splitLines(input)
+
+    for i, line in ipairs(lines) do
+        local x, y, z = line:match("(%d+),(%d+),(%d+)")
+        table.insert(boxes, {x=x, y=y, z=z, i=i, circuit=i})
+    end
+
+    local dists = {}
+    local circuits = {}
+
+    for i, box1 in ipairs(boxes) do
+        circuits[i] = i
+        for j=i+1, #boxes do
+            local box2 = boxes[j]
+            table.insert(dists, {
+                i=i,
+                j=j,
+                dist=puzzle1.dist(box1, box2)
+            })
+        end
+    end
+
+    table.sort(dists, function (a, b)
+        return a.dist < b.dist
+    end)
+
+    for _, d in ipairs(dists) do
+        local circ1 = circuits[d.i]
+        local circ2 = circuits[d.j]
+        
+        local connex = true
+        for k, v in pairs(circuits) do
+            if v == circ2 then
+                circuits[k] = circ1
+            elseif v ~= circ1 then
+                connex = false
+            end
+        end
+        if connex then
+            return boxes[d.i].x * boxes[d.j].x
+        end
+    end
+end
+
+return puzzle2