return (function()
local builders = {}
local function register(name, f)
builders[name] = f
end
register('llpeg', function() return require [[Module:User:Cscott/llpeg]] end)
register('pqueue', function(myrequire)
--[[ Priority Queue implemented in lua, based on a binary heap.
Copyright (C) 2017 Lucas de Morais Siqueira <lucas.morais.siqueira@gmail.com>
License: zlib
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgement in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
]]--
-- modified by xxopxe@gmail.com
local floor = math.floor
local PriorityQueue = {}
PriorityQueue.__index = PriorityQueue
setmetatable(
PriorityQueue,
{
__call = function ()
local new = {}
setmetatable(new, PriorityQueue)
new:initialize()
return new
end
}
)
function PriorityQueue:initialize()
--[[ Initialization.
Example:
PriorityQueue = require "priority_queue"
pq = PriorityQueue()
]]--
self.heap_val = {}
self.heap_pri = {}
self.current_size = 0
end
function PriorityQueue:empty()
return self.current_size == 0
end
function PriorityQueue:size()
return self.current_size
end
function PriorityQueue:swim()
-- Swim up on the tree and fix the order heap property.
local heap_val = self.heap_val
local heap_pri = self.heap_pri
local floor = floor
local i = self.current_size
while floor(i / 2) > 0 do
local half = floor(i / 2)
if heap_pri[i] < heap_pri[half] then
heap_val[i], heap_val[half] = heap_val[half], heap_val[i]
heap_pri[i], heap_pri[half] = heap_pri[half], heap_pri[i]
end
i = half
end
end
function PriorityQueue:put(v, p)
--[[ Put an item on the queue.
Args:
v: the item to be stored
p(number): the priority of the item
]]--
--
self.current_size = self.current_size + 1
self.heap_val[self.current_size] = v
self.heap_pri[self.current_size] = p
self:swim()
end
function PriorityQueue:sink()
-- Sink down on the tree and fix the order heap property.
local size = self.current_size
local heap_val = self.heap_val
local heap_pri = self.heap_pri
local i = 1
while (i * 2) <= size do
local mc = self:min_child(i)
if heap_pri[i] > heap_pri[mc] then
heap_val[i], heap_val[mc] = heap_val[mc], heap_val[i]
heap_pri[i], heap_pri[mc] = heap_pri[mc], heap_pri[i]
end
i = mc
end
end
function PriorityQueue:min_child(i)
if (i * 2) + 1 > self.current_size then
return i * 2
else
if self.heap_pri[i * 2] < self.heap_pri[i * 2 + 1] then
return i * 2
else
return i * 2 + 1
end
end
end
function PriorityQueue:pop()
-- Remove and return the top priority item
local heap_val = self.heap_val
local heap_pri = self.heap_pri
local retval, retprio = heap_val[1], heap_pri[1]
heap_val[1], heap_pri[1] = heap_val[self.current_size], heap_pri[self.current_size]
heap_val[self.current_size], heap_pri[self.current_size] = nil, nil
self.current_size = self.current_size - 1
self:sink()
return retval, retprio
end
function PriorityQueue:peek()
-- return the top priority item
return self.heap_val[1], self.heap_pri[1]
end
return PriorityQueue
end)
register('advent.compat', function() return require [[Module:User:Cscott/compat]] end)
register('eq', function(myrequire)
-- "fix" lua's eq metamethod to be consistent with __add etc, that is:
-- try the metamethod if any operand is not a number
local function eq(a, b)
local tya, tyb = type(a), type(b)
if tya ~= 'number' or tyb ~= 'number' then
local op = nil
local mt = getmetatable(a)
if mt ~= nil then op = mt.__eq end
if op == nil then
mt = getmetatable(b)
if mt ~= nil then op = mt.__eq end
end
if op ~= nil then
return op(a, b)
end
end
return a == b
end
return eq
end)
register('lt', function(myrequire)
-- "fix" lua's lt metamethod to be consistent with __add etc, that is:
-- try the metamethod if any operand is not a number
local function lt(a, b)
local tya, tyb = type(a), type(b)
if tya ~= 'number' or tyb ~= 'number' then
local op = nil
local mt = getmetatable(a)
if mt ~= nil then op = mt.__lt end
if op == nil then
mt = getmetatable(b)
if mt ~= nil then op = mt.__lt end
end
if op ~= nil then
return op(a, b)
end
end
return a < b
end
return lt
end)
register('bignum', function(myrequire)
local compat = myrequire('advent.compat')
local eq = myrequire('eq')
local lt = myrequire('lt')
-- poor man's bignum library
local RADIX = 1000 -- power of 10 to make printout easier
local function maxdigits(a, b)
if #a > #b then return #a end
return #b
end
local function ltz(a)
if type(a) == 'number' then
return a < 0
end
return a.negative or false
end
local BigNum = {}
BigNum.__index = BigNum
function BigNum:new(n)
if n == nil then n = 0 end
assert(type(n)=='number')
if n < 0 then
return setmetatable( {-n, negative=true}, self):normalize()
else
return setmetatable( {n}, self):normalize()
end
end
function BigNum:__tostring()
local result = {}
if self.negative then
table.insert(result, "-")
end
local first = true
for i=#self,1,-1 do
local n = self[i]
if n ~= 0 or not first then
local s = tostring(n)
if first then
first = false
else
while #s < 3 do s = '0' .. s end
end
table.insert(result, s)
end
end
if #result == 0 then return "0" end
return table.concat(result)
end
function BigNum:toNumber()
local m = 1
local sum = 0
for i=1,#self do
sum = sum + (self[i] * m)
m = m * RADIX
end
return sum
end
function BigNum:normalize()
local i = 1
local sawNonZero = false
while self[i] ~= nil do
assert(self[i] >= 0)
if self[i] > 0 then
sawNonZero = true
end
if self[i] >= 1000 then
local carry = math.floor(self[i] / 1000)
self[i] = self[i] % 1000
self[i+1] = (self[i+1] or 0) + carry
end
i = i + 1
end
if not sawNonZero then
self.negative = nil -- -0 is 0
end
return self
end
function BigNum:copy()
local r = BigNum:new()
for i=1,#self do
r[i] = self[i]
end
r.negative = self.negative
return r
end
function BigNum.__unm(a)
if eq(a, 0) then return a end -- -0 is 0
local r = a:copy()
r.negative = not r.negative
return r
end
function BigNum.__add(a, b)
if ltz(b) then
if ltz(a) then
return -((-a) + (-b))
end
return a - (-b)
end
if ltz(a) then
return b - (-a)
end
assert(not ltz(a))
assert(not ltz(b))
if type(a) == 'number' then
a,b = b,a
end
assert(not a.negative)
local r = a:copy()
if type(b) == 'number' then
assert(b >= 0)
r[1] = (r[1] or 0) + b
else
assert(not b.negative)
for i=1,#b do
r[i] = (r[i] or 0) + b[i]
end
end
return r:normalize()
end
function BigNum.__lt(a, b)
if ltz(a) then
if ltz(b) then
return (-a) > (-b)
end
return true
elseif ltz(b) then
return false
end
if type(a) == 'number' then a = BigNum:new(a) end
if type(b) == 'number' then b = BigNum:new(b) end
for i=maxdigits(a,b),1,-1 do
if (a[i] or 0) < (b[i] or 0) then return true end
if (a[i] or 0) > (b[i] or 0) then return false end
end
return false -- they are equal
end
function BigNum.__le(a, b)
return not (a > b)
end
function BigNum.__eq(a, b)
if ltz(a) ~= ltz(b) then return false end
if type(a) == 'number' then a = BigNum:new(a) end
if type(b) == 'number' then b = BigNum:new(b) end
for i=1,maxdigits(a,b) do
if (a[i] or 0) ~= (b[i] or 0) then return false end
end
return true
end
function BigNum.__sub(a, b)
if ltz(b) then
return a + (-b)
end
if ltz(a) then
return -((-a) + b)
end
if type(a) == 'number' then a = BigNum:new(a) end
if type(b) == 'number' then b = BigNum:new(b) end
if b > a then
return -(b - a)
end
local r = a:copy()
local borrow = 0
for i=1,maxdigits(a,b) do
r[i] = (r[i] or 0) - (b[i] or 0) - borrow
borrow = 0
while r[i] < 0 do
r[i] = r[i] + RADIX
borrow = borrow + 1
end
assert(r[i] >= 0)
end
assert(borrow == 0)
return r:normalize() -- shouldn't actually be necessary?
end
function BigNum.__mul(a, b)
if type(a) == 'number' then
a,b = b,a
end
local r = BigNum:new()
if type(b) == 'number' then
if b < 0 then r.negative = true ; b = -b ; end
assert(b>=0)
for i=1,#a do
r[i] = a[i] * b
end
if a.negative then r.negative = not r.negative end
return r:normalize()
end
for i=1,#a do
for j=1,#b do
assert(a[i] >= 0)
assert(b[j] >= 0)
local prod = a[i] * b[j]
r[i+j-1] = (r[i+j-1] or 0) + prod
end
end
r.negative = a.negative
if b.negative then r.negative = not r.negative end
return r:normalize()
end
function toBinary(a)
assert(not a.negative)
local bits = {}
local RADIX_DIV_2 = compat.idiv(RADIX, 2)
while a[1] ~= nil do
table.insert(bits, a[1] % 2)
for i=1,#a do
a[i] = compat.idiv(a[i], 2) + ((a[i+1] or 0) % 2) * RADIX_DIV_2
end
if a[#a] == 0 then a[#a] = nil end
end
return bits
end
local function divmod(a, b)
if eq(b, 0) then error("division by zero") end
if ltz(b) then
if ltz(a) then return divmod(-a, -b) end
local q,r = divmod(a, -b)
if lt(0, r) then q = q + 1 end
return -q, -r
elseif ltz(a) then
local q,r = divmod(-a, b)
if lt(0, r) then q = q + 1 end
return -q, r
end
-- ok, a and b are both positive now
assert(not ltz(a))
assert(not ltz(b))
if type(a) == 'number' then a = BigNum:new(a) end
if type(b) == 'number' then b = BigNum:new(b) end
local N,D = a,b
local Q,R = BigNum:new(0), BigNum:new(0)
local Nbits = toBinary(N:copy())
for i=#Nbits,1,-1 do
--print("R=",R,"Q=",Q)
for i=1,#R do R[i] = R[i] * 2 end
if Nbits[i] > 0 then R[1] = R[1] + 1 end
R:normalize()
for i=1,#Q do Q[i] = Q[i] * 2 end
if R >= D then
R = R - D
Q[1] = Q[1] + 1
end
Q:normalize()
end
return Q,R
end
function BigNum.__idiv(a, b)
local q,r = divmod(a, b)
return q
end
function BigNum.__mod(a, b)
local q,r = divmod(a, b)
return r
end
--[[
print(BigNum:new(4) >= BigNum:new(2))
print(BigNum:new(4) > BigNum:new(2))
print(BigNum:new(2) >= BigNum:new(2))
print(BigNum:new(2) > BigNum:new(2))
print(BigNum:new(4653) // BigNum:new(210))
]]--
return BigNum
end)
register('util', function(myrequire)
local function read_wiki_input(func)
return function (frame, ...)
if type(frame)=='string' then
frame = { args = { frame, ... } }
end
local title = mw.title.new(frame.args[1])
local source = title:getContent()
if source == nil then
error("Can't find title " .. tostring(title))
end
source = source:gsub("^%s*<syntaxhighlight[^>]*>\n?", "", 1)
source = source:gsub("</syntaxhighlight[^>]*>%s*$", "", 1)
return func(source, frame.args[2], frame.args[3])
end
end
return {
read_wiki_input = read_wiki_input,
}
end)
register('day21', function(myrequire)
--[[ DAY 21 ]]--
local l = myrequire('llpeg')
local PriorityQueue = myrequire('pqueue')
local BigNum = myrequire('bignum')
local read_wiki_input = myrequire('util').read_wiki_input
local compat = myrequire('advent.compat')
local TRACK_PATH = false
--[[ PARSING ]]--
local Block = {}
Block.__index = Block
local Rock = setmetatable({rock=true,type="#"}, Block)
Rock.__index = Rock
local Plot = setmetatable({plot=true,type="."}, Block)
Plot.__index = Plot
local Start = setmetatable({start=true,type="S"}, Plot)
Start.__index = Start
function Rock:__tostring() return "#" end
function Plot:__tostring()
if self.reached then return "O" end
if self.start then return "S" end
return "."
end
Start.__tostring = Plot.__tostring -- metamethods don't inherit (oddly)
local nl = l.P"\n"
local function make_block(type)
if type=='#' then return setmetatable({}, Rock) end
if type=='.' then return setmetatable({}, Plot) end
if type=='S' then return setmetatable({}, Start) end
error("unknown block type: "..type)
end
local patt = l.P{
"Graph",
Graph = l.Ct( l.V"Row" * (nl^1 * l.V"Row")^0 * nl^0) * -1,
Row = l.Ct( l.V"Block"^1 ),
Block = l.S".#S" / make_block,
}
local Graph = {}
Graph.__index = Graph
local function parse(source, addWarp)
local ast, errlabel, pos = patt:match(source)
if not ast then
error(string.format("Error at pos %s label '%s'", pos, errlabel))
end
--print('Parsed with success!')
return Graph:new(ast):link(addWarp)
end
--[[ Part 1 ]]--
function Graph:new(data)
return setmetatable({ data=data }, self)
end
function Graph:at(row,col,default)
return ((self.data or {})[row] or {})[col] or default
end
function Graph:foreach(func) -- r,c,val actually
for r,row in pairs(self.data or {}) do
for c,val in pairs(row) do
func(r,c,val)
end
end
end
local function compare_rc(a, b)
if a.r < b.r then return true end
if a.r > b.r then return false end
if a.c < b.c then return true end
if a.c > b.c then return false end
-- elements are equal
return false
end
function Graph:hash(func)
local accum = {}
local coords = {}
self:foreach(function(r,c,val)
table.insert(coords, {r=r,c=c,val=func(val)})
end)
table.sort(coords, compare_rc)
for _,v in ipairs(coords) do
table.insert(accum, string.format("%d,%d,%s;", v.r,v.c, v.val))
end
return table.concat(accum)
end
function Graph:set(row,col,val)
if self.data == nil then
self.data = {}
end
if self.data[row] == nil then
self.data[row] = {}
end
self.data[row][col] = val
end
function Graph:setDefault(row,col,valfunc)
local val = self:at(row, col)
if val ~= nil then return val end
if type(valfunc) == 'function' then
val = valfunc()
else
val = valfunc
end
self:set(row, col, val)
return val
end
function Graph:rowN()
return #(self.data)
end
function Graph:colN()
return #(self.data[1])
end
function Graph:print()
for r,row in ipairs(self.data) do
for c,val in ipairs(row) do
if val == nil then
val = " "
end
io.write(tostring(val))
end
io.write("\n")
end
end
function Graph:link(addWarp)
for r=1,self:rowN() do
for c=1,self:colN() do
local sp = self:at(r,c)
sp.r, sp.c = r,c
if r > 1 then
sp.n = self:at(r-1,c)
elseif addWarp then
sp.n = { warp=self:at(self:rowN(), c), r=-1, c=0 }
end
if c > 1 then
sp.w = self:at(r,c-1)
elseif addWarp then
sp.w = { warp=self:at(r, self:colN()), r=0, c=-1 }
end
if r < self:rowN() then
sp.s = self:at(r+1,c)
elseif addWarp then
sp.s = { warp=self:at(1,c), r=1, c=0 }
end
if c < self:colN() then
sp.e = self:at(r,c+1)
elseif addWarp then
sp.e = { warp=self:at(r,1), r=0, c=1 }
end
if sp.start == true then self.start = {r=r, c=c} end
end
end
return self
end
local directions = { "n", "e", "s", "w" }
function Graph:search1(start, steps)
local Q = PriorityQueue()
local sp = self:at(start.r, start.c)
local reachCount = 0
local parity = steps % 2
sp.reached = true
Q:put({sp=sp,steps=0}, 0)
while not Q:empty() do
local state = Q:pop()
if state.steps % 2 == parity then reachCount = reachCount + 1 end
if state.steps < steps then
local nextSteps = state.steps + 1
for _,d in ipairs(directions) do
local next = state.sp[d]
if next ~= nil and not next.rock and not next.reached then
next.reached = true
Q:put({sp=next,steps=nextSteps}, nextSteps)
end
end
end
end
return reachCount
end
local function part1(source, amt)
local graph = parse(source)
--graph:print()
--print()
local n = graph:search1(graph.start, amt or 64)
--graph:print()
return n
end
--[[ PART 2 ]]--
local function sortedKeys(tbl)
local sorted = {}
for k,_ in pairs(tbl) do
table.insert(sorted, k)
end
table.sort(sorted)
return sorted
end
function Graph:search2(start, steps)
local sp = self:at(start.r, start.c)
local parity = steps % 2
local metagraph = Graph:new()
local function metagraphAt(mr, mc)
return metagraph:setDefault(mr, mc, function()
return { r=mr, c=mc, g=Graph:new() }
end)
end
local function setReached(meta, sp)
meta.g:set(sp.r, sp.c, true)
end
local function reached(meta, sp)
return meta.g:at(sp.r, sp.c) ~= nil
end
local function hash(frontier)
local accum = {}
local coords = {}
for _,v in ipairs(frontier) do
-- ignore meta, ignore steps
table.insert(coords, {r=v.sp.r,c=v.sp.c})
end
table.sort(coords, compare_rc)
for _,v in ipairs(coords) do
table.insert(accum, string.format("%d,%d;", v.r, v.c))
end
return table.concat(accum)
end
local memo = {}
local id = 1
local firstLoop = nil
local function doOne(currentFrontier, metaNext, seen)
local key = hash(currentFrontier)
if memo[key] ~= nil then
--print("seen", currentFrontier[1].meta.r, currentFrontier[1].meta.c)
if firstLoop == nil then
firstLoop = currentFrontier[1].steps
--print("First loop", firstLoop)
end
else
memo[key] = { id=id }
id = id + 1
end
local reachCount = 0
local nextFrontier = {}
for i=1,#currentFrontier do
local state = currentFrontier[i]
if state.steps % 2 == parity then reachCount = reachCount + 1 end
if state.steps < steps then
local nextSteps = state.steps + 1
for _,d in ipairs(directions) do
local nextmeta = state.meta
local next = state.sp[d]
if next ~= nil and next.warp ~= nil then
local mr, mc = nextmeta.r + next.r, nextmeta.c + next.c
nextmeta = metagraphAt(mr, mc)
next = next.warp
end
if next ~= nil and not next.rock and not reached(nextmeta, next) then
setReached(nextmeta, next)
-- collect the 'nextFrontier' by metablock
local nextFrontier = metaNext:setDefault(nextmeta.r, nextmeta.c, {})
table.insert(nextFrontier, {meta=nextmeta,sp=next,steps=nextSteps})
end
end
end
end
if memo[key].reachCount == nil then
memo[key].reachCount = reachCount
else
memo[key].bad = true
end
seen[memo[key].id] = (seen[memo[key].id] or 0) + 1
return reachCount
end
local reachCount = 0
local currentFrontier = Graph:new()
currentFrontier:set(0,0,{ {meta=metagraphAt(0,0),sp=sp,steps=0} })
setReached(metagraphAt(0,0), sp)
--local last = {0,0,0,0,0,0}
local bigSum = {}
repeat
local count=0
local metaNext = Graph:new()
local seen = {}
local steps = nil
currentFrontier:foreach(function(mr,mc,frontier)
reachCount = reachCount + doOne(frontier, metaNext, seen)
count = count + 1
steps = frontier[1].steps
end)
currentFrontier = metaNext
-- print status
if false then
local buf = {}
for _,v in ipairs(sortedKeys(seen)) do
table.insert(buf, string.format("%d=%d ", v, seen[v]))
end
--print("Steps", steps, reachCount, table.concat(buf))
end
if false then
if (steps % (2*131)) == 65 then
print("Steps", steps, reachCount)
end
local era = compat.idiv(steps, 131)
if bigSum[era] == nil then bigSum[era] = {} end
for i,v in pairs(seen) do
bigSum[era][i] = (bigSum[era][i] or 0) + v
end
if (steps % 131) == 130 and false then
local buf = {}
for _,v in ipairs(sortedKeys(bigSum[era])) do
table.insert(buf, string.format("%d=%d ", v, bigSum[era][v]))
end
--print(table.concat(buf))
end
end
until count == 0
return reachCount
end
--[[
We have a cycle of length 131: (first repeated occurrence of a block is at step 197)
Steps 131 392=1 393=1 394=1 395=1
Steps 262 392=1 393=1 394=1 395=1 1436=1 1437=1 1438=1 1439=1
Steps 393 392=1 393=1 394=1 395=1 1436=2 1437=2 1438=2 1439=2
Steps 524 392=1 393=1 394=1 395=1 1436=3 1437=3 1438=3 1439=3
And also at points in the middle of the cycle:
Steps 300 692=2 693=1 694=2 695=1 696=1 697=2 698=1 699=2 1588=1 1589=1 1590=1 1591=1
Steps 431 692=3 693=1 694=3 695=1 696=1 697=3 698=1 699=3 1588=2 1589=2 1590=2 1591=2
Steps 562 692=4 693=1 694=4 695=1 696=1 697=4 698=1 699=4 1588=3 1589=3 1590=3 1591=3
Look at the total reach count at correspondings points in the
cycle. NOTE THAT THE PARITY FLIPS EACH TIME because 131 is odd, so
we should only compare "odd" cycles with "odd" cycles. Be careful
you give the desired ending length when you run the program, or
you'll get sums for the wrong parity!
We want 26501365 steps, which is 101150 * 2*131 + 65!
Luckily, our trick still works!
Steps 327 94909 212122 121080
Steps 589 307031 333202 121080
Steps 851 640233 454282
Steps 1113 1094515
Steps 1375 1669877
Step N*2*131+65 = a*N^2 + b*N + c; solve
N=1 => 94909 = a + b + c 3a + b = 212122 2a=121080 a=60540
N=2 => 307031 = 4a + 2b + c 5a + b = 333202 b=30502
N=3 => 640233 = 9a + 3b + c c=3867
After N*2*131+65 steps, reaches: 60540 * N^2 + 30502 * N + 3867
Solve for N=23, 6091 steps: 32731073
Solve for N=101150 => 619407349431167
]]--
local function part2(source, amt)
local graph = parse(source, true) -- with warps
local N1 = graph:search2(graph.start, 1*2*131+65)
local N2 = graph:search2(graph.start, 2*2*131+65)
local N3 = graph:search2(graph.start, 3*2*131+65)
local N2mN1 = N2 - N1 -- 212122
local N3mN2 = N3 - N2 -- 333202
local a = compat.idiv(N3mN2 - N2mN1, 2)
local b = N2mN1 - 3*a
local c = N1 - a - b
--print(N1, N2, N3, a, b, c)
local N = compat.idiv(BigNum:new(amt) - 65, 2*131)
return N*N*a + N*b + c
end
--[[ CLI ] ]--
local source = io.input("day21.input"):read("*a")
print('Plots:', part1(source, 6))
-- print('Infinite Plots:', part2(source, 6)) -- 44
-- print('Infinite Plots:', part2(source, 10)) -- 110
-- print('Infinite Plots:', part2(source, 50)) -- 2268
-- print('Infinite Plots:', part2(source, 100)) -- 8993
-- print('Infinite Plots:', part2(source, 500)) -- 221398
-- print('Infinite Plots:', part2(source, 1000)) -- 884098
-- print('Infinite Plots:', part2(source, 5000)) -- 22056540
-- print('Infinite Plots:', part2(source, 64)) -- 3751
-- print('Infinite Plots:', part2(source, 64+131)) --33904
-- print('Infinite Plots:', part2(source, 64+2*131)) -- 94327
-- print('Infinite Plots:', part2(source, 64+5*131)) -- 457216
-- print('Infinite Plots:', part2(source, 64+10*131)) -- 1667431
-- print('Infinite Plots:', part2(source, 64+20*131)) -- 6358111
-- print('Infinite Plots:', part2(source, 64+30*131)) -- 14075791
print('Infinite Plots:', part2(source, 26501365)) -- 3751
--[ [ END CLI ]]--
return {
part1 = read_wiki_input(part1),
part2 = read_wiki_input(part2),
}
end)
local modules = {}
modules['bit32'] = require('bit32')
modules['string'] = require('string')
modules['strict'] = {}
modules['table'] = require('table')
local function myrequire(name)
if modules[name] == nil then
modules[name] = true
modules[name] = (builders[name])(myrequire)
end
return modules[name]
end
return myrequire('day21')
end)()
