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Felix Van der Jeugt 2021-12-18 15:51:21 +01:00
parent 6005fb089d
commit 9efab871b1
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3 changed files with 277 additions and 1 deletions

141
day18/part1.lua Executable file
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@ -0,0 +1,141 @@
#!/usr/bin/env luajit
require("utils")
function parse(line)
local number = {}
local depth = 0
for char in chars(line) do
if char == "[" then
depth = depth + 1
elseif char == "]" then
depth = depth - 1
elseif char ~= "," then
table.insert(number, { d=depth, n=tonumber(char) })
end
end
return number
end
function add(a, b)
local sum = {}
for i, digit in ipairs(a) do
table.insert(sum, { d = digit.d + 1, n = digit.n })
end
for i, digit in ipairs(b) do
table.insert(sum, { d = digit.d + 1, n = digit.n })
end
return sum
end
function explode(a)
local new = {}
local exploded = false
local i = 1
while i <= #a do
if exploded or a[i].d <= 4 then
table.insert(new, a[i])
i = i + 1
else
exploded = true
if #new > 0 then
new[#new].n = new[#new].n + a[i].n
end
table.insert(new, { d = a[i].d - 1, n = 0 })
if #a >= i + 2 then
table.insert(new, { d = a[i + 2].d, n = a[i + 1].n + a[i + 2].n })
end
i = i + 3
end
end
return exploded, new
end
-- printtable({ explode(parse("[[[[[9,8],1],2],3],4]")) })
-- printtable({ explode(parse("[7,[6,[5,[4,[3,2]]]]]")) })
-- printtable({ explode(parse("[[6,[5,[4,[3,2]]]],1]")) })
-- printtable({ explode(parse("[[3,[2,[1,[7,3]]]],[6,[5,[4,[3,2]]]]]")) })
-- printtable({ explode(parse("[[3,[2,[8,0]]],[9,[5,[4,[3,2]]]]]")) })
function split(a)
local new = {}
local split = false
for i, digit in ipairs(a) do
if split or digit.n < 10 then
table.insert(new, digit)
else
split = true
table.insert(new, { d = digit.d + 1, n = math.floor(digit.n / 2) })
table.insert(new, { d = digit.d + 1, n = math.ceil(digit.n / 2) })
end
end
return split, new
end
function reduce(a)
local changed = true
repeat
changed, a = explode(a)
if not changed then
changed, a = split(a)
end
until not changed
return a
end
function reconstruct(number)
local function go(d, c)
local left, right
if number[c].d > d then
left, c = go(d + 1, c)
right, c = go(d + 1, c)
return { left, right }, c
else
return number[c].n, c + 1
end
end
return go(0, 1)
end
function printnumber(a)
local function go(a)
if type(a) == "number" then
io.write(tostring(a))
else
io.write("[")
go(a[1])
io.write(",")
go(a[2])
io.write("]")
end
end
go(reconstruct(a))
io.write("\n")
end
-- printnumber(reduce(parse("[[[[[4,3],4],4],[7,[[8,4],9]]],[1,1]]")))
-- printnumber(reduce(add(parse("[[[[4,3],4],4],[7,[[8,4],9]]]"),parse("[1,1]"))))
-- printnumber(parse("[[[0,[4,5]],[0,0]],[[[4,5],[2,6]],[9,5]]]"))
-- printtable(parse("[[[0,[4,5]],[0,0]],[[[4,5],[2,6]],[9,5]]]"))
-- printnumber(add(parse("[[[0,[4,5]],[0,0]],[[[4,5],[2,6]],[9,5]]]"),parse("[7,[[[3,7],[4,3]],[[6,3],[8,8]]]]")))
-- printnumber(reduce(add(parse("[[[0,[4,5]],[0,0]],[[[4,5],[2,6]],[9,5]]]"),parse("[7,[[[3,7],[4,3]],[[6,3],[8,8]]]]"))))
function magnitude(a)
local function go(a)
if type(a) == "number" then
return a
else
return 3 * go(a[1]) + 2 * go(a[2])
end
end
return go(reconstruct(a))
end
local f = io.open(arg[3])
local number = parse(f:read("*l"))
local line = f:read("*l")
while line do
number = reduce(add(number, parse(line)))
line = f:read("*l")
end
print(magnitude(number))

135
day18/part2.lua Executable file
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#!/usr/bin/env luajit
require("utils")
function parse(line)
local number = {}
local depth = 0
for char in chars(line) do
if char == "[" then
depth = depth + 1
elseif char == "]" then
depth = depth - 1
elseif char ~= "," then
table.insert(number, { d=depth, n=tonumber(char) })
end
end
return number
end
function explode(a)
local new = {}
local exploded = false
local i = 1
while i <= #a do
if exploded or a[i].d <= 4 then
table.insert(new, a[i])
i = i + 1
else
exploded = true
if #new > 0 then
new[#new].n = new[#new].n + a[i].n
end
table.insert(new, { d = a[i].d - 1, n = 0 })
if #a >= i + 2 then
table.insert(new, { d = a[i + 2].d, n = a[i + 1].n + a[i + 2].n })
end
i = i + 3
end
end
return exploded, new
end
function split(a)
local new = {}
local split = false
for i, digit in ipairs(a) do
if split or digit.n < 10 then
table.insert(new, digit)
else
split = true
table.insert(new, { d = digit.d + 1, n = math.floor(digit.n / 2) })
table.insert(new, { d = digit.d + 1, n = math.ceil(digit.n / 2) })
end
end
return split, new
end
function reduce(a)
local changed = true
repeat
changed, a = explode(a)
if not changed then
changed, a = split(a)
end
until not changed
return a
end
function add(a, b)
local sum = {}
for i, digit in ipairs(a) do
table.insert(sum, { d = digit.d + 1, n = digit.n })
end
for i, digit in ipairs(b) do
table.insert(sum, { d = digit.d + 1, n = digit.n })
end
return reduce(sum)
end
function reconstruct(number)
local function go(d, c)
local left, right
if number[c].d > d then
left, c = go(d + 1, c)
right, c = go(d + 1, c)
return { left, right }, c
else
return number[c].n, c + 1
end
end
return go(0, 1)
end
function printnumber(a)
local function go(a)
if type(a) == "number" then
io.write(tostring(a))
else
io.write("[")
go(a[1])
io.write(",")
go(a[2])
io.write("]")
end
end
go(reconstruct(a))
io.write("\n")
end
function magnitude(a)
local function go(a)
if type(a) == "number" then
return a
else
return 3 * go(a[1]) + 2 * go(a[2])
end
end
return go(reconstruct(a))
end
local numbers = {}
for line in io.lines(arg[3]) do
table.insert(numbers, parse(line))
end
local max = 0
for i, a in pairs(numbers) do
for j, b in pairs(numbers) do
if i ~= j then
local m = magnitude(add(a, b))
if m > max then max = m end
end
end
end
print(max)

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@ -32,7 +32,7 @@ function printtable(t, nonewline)
printtable(v, true) printtable(v, true)
io.write(") ") io.write(") ")
else else
io.write(v.." ") io.write(tostring(v).." ")
end end
end end
if not nonewline then if not nonewline then