Dumping 2023 Solutions

2023/day-10/demo-input.txt

@@ -0,0 +1,5 @@
+-L|F7
+7S-7|
+L|7||
+-L-J|
+L|-JF

2023/day-10/part1.lua

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+require("lib")
+
+local input = GetInput()
+
+--[[
+|   is a vertical pipe connecting north and south.
+-   is a horizontal pipe connecting east and west.
+L   is a 90-degree bend connecting north and east.
+J   is a 90-degree bend connecting north and west.
+7   is a 90-degree bend connecting south and west.
+F   is a 90-degree bend connecting south and east.
+.   is ground; there is no pipe in this tile.
+S   is the starting position of the animal; there is a pipe on this tile, but your sketch doesn't show what shape the pipe has.
+]]--
+
+-- Find starting position
+-- Find the two starting pipes accordingly from starting position
+-- Loop twice from starting position until both loops are at the same coordinate
+-- Count the steps
+
+local pipeSymbols = {
+    ["north"] = {"|", "L", "J"},
+    ["east"] = {"-", "L", "F"},
+    ["south"] = {"|", "7", "F"},
+    ["west"] = {"-", "J", "7"}
+}
+
+local function findStartPipes(x, y)
+    local maxRight = math.min(x+1, #input[y])
+    local maxLeft = math.max(x-1, 1)
+
+    local north = input[math.max(y-1, 1)]:sub(x, x)
+    local south = input[math.min(y+1, #input)]:sub(x, x)
+    local east = input[y]:sub(maxRight, maxRight)
+    local west = input[y]:sub(maxLeft, maxLeft)
+
+    local t = {}
+    if north and table.contains(pipeSymbols.south, north) then
+        t[#t+1] = {currentPos = {x = x, y = y-1}, lastPos = {x = x, y = y}}
+    end
+    if east and table.contains(pipeSymbols.west, east) then
+        t[#t+1] = {currentPos = {x = x+1, y = y}, lastPos = {x = x, y = y}}
+    end
+    if south and table.contains(pipeSymbols.north, south) then
+        t[#t+1] = {currentPos = {x = x, y = y+1}, lastPos = {x = x, y = y}}
+    end
+    if west and table.contains(pipeSymbols.east, west) then
+        t[#t+1] = {currentPos = {x = x-1, y = y}, lastPos = {x = x, y = y}}
+    end
+    return t
+end
+
+local function checkDirection(path, symbol, dir, x, y)
+    local oppositeDir = {["north"] = "south", ["south"] = "north", ["east"] = "west", ["west"] = "east"}
+    local currentSymbol = input[path.currentPos.y]:sub(path.currentPos.x, path.currentPos.x)
+    local newX, newY = path.currentPos.x + x, path.currentPos.y + y
+    if (x ~= 0 and path.lastPos.x ~= newX) or (y ~= 0 and path.lastPos.y ~= newY) then
+        if table.contains(pipeSymbols[dir], currentSymbol) then
+            if symbol and table.contains(pipeSymbols[oppositeDir[dir]], symbol) then
+                return {currentPos = {x = newX, y = newY}, lastPos = {x = path.currentPos.x, y = path.currentPos.y}}
+            end
+        end
+    end
+    return nil
+end
+
+local function runPipes(path)
+    local x, y = path.currentPos.x, path.currentPos.y
+
+    local maxRight = math.min(x+1, #input[y])
+    local maxLeft = math.max(x-1, 1)
+
+    local north = input[math.max(y-1, 1)]:sub(x, x)
+    local south = input[math.min(y+1, #input)]:sub(x, x)
+    local east = input[y]:sub(maxRight, maxRight)
+    local west = input[y]:sub(maxLeft, maxLeft)
+
+    return checkDirection(path, north, "north", 0, -1) or
+        checkDirection(path, east, "east", 1, 0) or
+        checkDirection(path, south, "south", 0, 1) or
+        checkDirection(path, west, "west", -1, 0)
+end
+
+local function pipesTouching(pathsTable)
+    if pathsTable[1].currentPos.x == pathsTable[2].currentPos.x and
+    pathsTable[1].currentPos.y == pathsTable[2].currentPos.y then
+        return true
+    end
+    return false
+end
+
+local function pipes()
+    local sum = 1 -- Start at 1 because finding start pipes doesn't include a +1
+    local paths
+
+    for row, str in ipairs(input) do
+        local start = str:find("S")
+        if start then
+            paths = findStartPipes(start, row)
+        end
+    end
+
+    while not pipesTouching(paths) do
+        sum = sum + 1
+        for i = 1, #paths do
+            paths[i] = runPipes(paths[i])
+        end
+    end
+    return sum
+end
+
+print("How many steps along the loop does it take to get from the starting position to the point farthest from the starting position?\nAnswer: " .. pipes())

2023/day-12/demo-input.txt

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+???.### 1,1,3
+.??..??...?##. 1,1,3
+?#?#?#?#?#?#?#? 1,3,1,6
+????.#...#... 4,1,1
+????.######..#####. 1,6,5
+?###???????? 3,2,1