solved day 2 part 2

02-1/main.lua

@@ -0,0 +1,74 @@
+#!/usr/bin/env lua
+
+function file_exists(file)
+      local f = io.open(file, "rb")
+      if f then f:close() end
+      return f ~= nil
+end
+
+-- get all lines from a file, returns an empty 
+-- list/table if the file does not exist
+function lines_from(file)
+  if not file_exists(file) then return {} end
+  lines = {}
+  for line in io.lines(file) do 
+    lines[#lines + 1] = line
+  end
+  return lines
+end
+
+function atoi_list(strings)
+    local ints = {}
+    for i,s in ipairs(strings) do
+       ints[#ints + 1] = tonumber(s)
+    end
+    return ints
+end
+
+function toSlices(ints)
+    local slices = {}
+    for k,i in ipairs(ints) do
+        if(k < (#ints - 1)) then
+            slices[k] = ints[k] + ints[k+1] + ints[k+2]
+        end
+    end
+    return slices
+end
+
+function split(s, delimiter)
+    result = {};
+    for match in (s..delimiter):gmatch("(.-)"..delimiter) do
+        table.insert(result, match);
+    end
+    return result;
+end
+
+-------------------------------------------------
+file = "input.txt"
+
+local v,h,aim = 0,0,0
+
+allLines = lines_from(file)
+
+for i,l in ipairs(allLines) do
+    local current = split(l, ' ')
+    local cmd = current[1]
+    local X = current[2]
+    if(cmd == "down") then
+        aim = aim + X
+    end
+    if(cmd == "up") then
+        aim = aim - X
+    end
+    if(cmd == "forward") then
+        h = h + X
+        v = v + (aim * X)
+    end
+end
+
+print("vertical position: " .. v)
+print("horizontal position: " .. h)
+
+local result = v * h
+
+io.write("The answer is ", result, ". Congrats, I hope!\n")