add day 3

1 files changed, 110 insertions, 0 deletions

diff --git a/03.lua b/03.lua
new file mode 100755
index 0000000..4cf692f
--- /dev/null
+++ b/03.lua
@@ -0,0 +1,110 @@
+#!/usr/bin/env lua
+
+local function expand(l, i)
+	local p = { i, i }
+	while p[1] > 1 and string.gmatch(l:sub(p[1] - 1, p[1] - 1), "%d")() ~= nil do
+		p[1] = p[1] - 1
+	end
+	while p[2] < #l and string.gmatch(l:sub(p[2] + 1, p[2] + 1), "%d")() ~= nil do
+		p[2] = p[2] + 1
+	end
+	return p
+end
+
+local function replace(l, s, e)
+	local t = {}
+	for token in string.gmatch(l, ".") do
+		table.insert(t, token)
+	end
+	for i = 1, #t do
+		if i >= s and i <= e then
+			t[i] = "."
+		end
+	end
+	return table.concat(t)
+end
+
+local function copy(v)
+	local j = {}
+	for i = 1, #v do
+		j[i] = v[i]
+	end
+	return j
+end
+
+local function adj(i, j)
+  return {
+    { i - 1, j },
+    { i + 1, j },
+    { i, j - 1 },
+    { i, j + 1 },
+    { i - 1, j - 1 },
+    { i - 1, j + 1 },
+    { i + 1, j - 1 },
+    { i + 1, j + 1 },
+  }
+end
+
+local function p1(l)
+	local v = copy(l)
+	local s = 0
+	for i = 1, #v do
+		for j = 1, #v[i] do
+			if string.gmatch(v[i]:sub(j, j), "[*#+$=@%%/&-]")() ~= nil then
+				local p = adj(i, j)
+				for k = 1, #p do
+					if
+						(p[k][1] < 1 or p[k][2] < 1 or p[k][1] > #v or p[k][2] > #v[p[k][1]])
+						or (string.gmatch(v[p[k][1]]:sub(p[k][2], p[k][2]), "%d")() == nil)
+					then
+						goto nextkp1
+					end
+					local pos = expand(v[p[k][1]], p[k][2])
+					s = s + tonumber(v[p[k][1]]:sub(pos[1], pos[2]))
+					v[p[k][1]] = replace(v[p[k][1]], pos[1], pos[2])
+					::nextkp1::
+				end
+			end
+		end
+	end
+	return s
+end
+
+local function p2(l)
+	local v = copy(l)
+	local s = 0
+	for i = 1, #v do
+		for j = 1, #v[i] do
+			if string.gmatch(v[i]:sub(j, j), "[*]")() ~= nil then
+				local p = adj(i, j)
+				local n = {}
+				for k = 1, #p do
+					if
+						(p[k][1] < 1 or p[k][2] < 1 or p[k][1] > #v or p[k][2] > #v[p[k][1]])
+						or (string.gmatch(v[p[k][1]]:sub(p[k][2], p[k][2]), "%d")() == nil)
+					then
+						goto nextkp2
+					end
+					local pos = expand(v[p[k][1]], p[k][2])
+					table.insert(n, tonumber(v[p[k][1]]:sub(pos[1], pos[2])))
+					v[p[k][1]] = replace(v[p[k][1]], pos[1], pos[2])
+					::nextkp2::
+				end
+				if #n == 2 then
+					s = s + n[1] * n[2]
+				end
+			end
+		end
+	end
+	return s
+end
+
+local f = io.open("03.txt", "r")
+local content = f:read("*all")
+f:close()
+local l = {}
+for line in string.gmatch(content, "[(%w%p)]+") do
+	table.insert(l, line)
+end
+print(p1(l))
+print(p2(l))