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('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('day23', function(myrequire)
--[[ DAY 23 ]]--
local l = myrequire('llpeg')
local PriorityQueue = myrequire('pqueue')
local read_wiki_input = myrequire('util').read_wiki_input
--[[ PARSING ]]--
local Block = {}
Block.__index = Block
function Block:new(args)
return setmetatable(args, self)
end
function Block:__tostring()
return string.format("r=%d,c=%d,ty=%s", self.r, self.c, self.type)
end
local nl = l.P"\n"
local function make_block(s)
return Block:new{type=s}
end
local directions = { 'n', 'e', 's', 'w' }
local dirmap = {
n= '^',
s= 'v',
e= '>',
w= '<',
['^'] = 'n',
['v'] = 's',
['>'] = 'e',
['<'] = 'w',
}
local oppositemap = {
n = 's',
s = 'n',
e = 'w',
w = 'e',
}
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".#^>v<" / make_block,
}
local ManhattanGraph = {}
ManhattanGraph.__index = ManhattanGraph
local function parse(source, isDry)
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 ManhattanGraph:new(ast):link(isDry)
end
--[[ Part 1 ]]--
function ManhattanGraph:new(data)
return setmetatable({ data=data }, self)
end
function ManhattanGraph:at(row,col,default)
return (self.data[row] or {})[col] or default
end
function ManhattanGraph:rowN()
return #(self.data)
end
function ManhattanGraph:colN()
return #(self.data[1])
end
function ManhattanGraph:print(coords)
for r,row in ipairs(self.data) do
for c,val in ipairs(row) do
if val == nil then
val = " "
elseif coords then
if val.type == '#' then
val = '##### '
else
val = string.format("%2d,%2d ",r,c)
end
else
val = val.type
end
io.write(tostring(val))
end
io.write("\n")
end
end
function ManhattanGraph:link(isDry)
local function maybe(sp, dir, r, c)
if sp.type == '#' then return nil end
if r < 1 or c < 1 then return nil end
if r > self:rowN() or c > self:colN() then return nil end
local spSlope = dirmap[sp.type]
if isDry then spSlope = nil end
if spSlope ~= nil and dir ~= spSlope then return nil end
local next = self:at(r,c)
if next.type == '#' then return nil end
local nextSlope = dirmap[next.type]
if isDry then nextSlope = nil end
if nextSlope ~= nil and nextSlope == oppositemap[dir] then return nil end
return next
end
for r=1,self:rowN() do
for c=1,self:colN() do
local sp = self:at(r,c)
sp.r, sp.c = r,c
sp.n = maybe(sp, 'n', r-1, c)
sp.s = maybe(sp, 's', r+1, c)
sp.e = maybe(sp, 'e', r, c+1)
sp.w = maybe(sp, 'w', r, c-1)
--[[
local function print_one(d)
print(string.format("%s dir %s connected to %s", sp, d, sp[d]))
end
for _,d in ipairs(directions) do
if sp[d] ~= nil then print_one(d) end
end
]]--
end
end
return self
end
function ManhattanGraph:findEntryExit(row)
-- Find the starting node
for i=1,self:colN() do
if self:at(row, i).type == '.' then
return self:at(row, i)
end
end
error("couldn't find it")
end
local Node = {}
Node.__index = Node
function Node:new(old, key)
return setmetatable({ old=old, edges={}, incoming={}, key=key }, self)
end
function Node:__tostring()
local buf = { "(", tostring(self.old), ")=>{" }
for _,e in ipairs(self.edges) do
table.insert(buf, tostring(e.cost))
table.insert(buf, "=(")
table.insert(buf, tostring(e.to.old))
table.insert(buf, "),")
end
table.insert(buf, "}")
return table.concat(buf)
end
function ManhattanGraph:compress(isDry)
-- Find the starting node and exit node
local start =self:findEntryExit(1)
local exit = self:findEntryExit(self:rowN())
local POSTEXIT = setmetatable({},{__tostring=function() return 'POSTEXIT' end})
-- now walk the maze creating nodes only when there is >1 exit possible
local nodeMap = {}
local function makeNewNode(old, key)
local newNode = Node:new(old, key)
assert(nodeMap[old] == nil)
nodeMap[old] = newNode
return newNode
end
local function connect(from, to, cost)
--print("Connecting", from, "to", to)
table.insert(from.edges, {to=to, cost=cost})
table.insert(to.incoming, {from=from, cost=cost})
end
local newStart = makeNewNode(start, start)
newStart.start = true
local worklist = { { new=newStart, old=start, cost=0 } }
local i = 1
while i <= #worklist do
local todo = worklist[i] ; i = i + 1
local validExits = {}
--nodeMap[todo.old] = todo.new
for _,d in ipairs(directions) do
if todo.old[d] ~= nil and todo.last ~= oppositemap[d] then
table.insert(validExits, d)
end
end
--print("visiting new=", todo.new, "old=",todo.old, "exits",#validExits)
if #validExits == 0 then
-- dead end. But maybe the exit?
if todo.old == exit then
local newExit = nodeMap[POSTEXIT]
if newExit == nil then
newExit = makeNewNode(POSTEXIT, exit)
newExit.exit = true
end
connect(todo.new, newExit, todo.cost)
end
elseif #validExits == 1 then
-- put this back on the worklist with the same origin node
local d = validExits[1]
table.insert(worklist, {new=todo.new, old=todo.old[d], last=d, cost=todo.cost+1})
else
-- ok, create a new node because there are multiple ways to go here.
-- but key these off a single intersection to prevent shenanigans
for _,d in ipairs(validExits) do
local nextNode = nodeMap[todo.old[d]]
if nextNode == nil then
--print("making new node for",d,todo.old[d])
nextNode = makeNewNode(todo.old[d], todo.old)
table.insert(worklist, {new=nextNode, old=todo.old[d], last=d, cost=0})
end
connect(todo.new, nextNode, todo.cost + 1) -- link up edges!
end
end
end
return newStart
end
function Node:topoSort()
local seen = {}
local S = { self }
local L = {}
local i = 1
while i <= #S do
local n = S[i] ; i = i + 1
seen[n] = true
table.insert(L, n)
for _,e in ipairs(n.edges) do
local m = e.to
seen[m] = true
m.topo = (m.topo or 0) + 1
if m.topo == #m.incoming then
table.insert(S, m)
end
end
end
-- check for cycles
for m,_ in pairs(seen) do
if (m.topo or 0) < #m.incoming then
error("at least one cycle: "..tostring(m))
end
m.topo = nil
end
return L -- a topologically sorted order
end
local function part1(source)
local mgraph = parse(source)
--mgraph:print()
local start = mgraph:compress()
-- longest path: just do shortest path on -G graph, SO LONG AS THIS IS A DAG
for _,n in ipairs(start:topoSort()) do
local max = 0
for _,m in ipairs(n.incoming) do
if m.cost + m.from.cost > max then max = m.cost + m.from.cost end
end
n.cost = max
--print(string.format("Longest path to %s is %d", n, max))
if n.exit ~= nil then return n.cost end
end
end
--[[ PART 2 ]]--
function longest_path(node, cost, seen, level)
--print(tostring(node))
if node.exit then return cost end -- yay
-- do this the hard way
seen[node.key] = true
local max = nil
for _,e in ipairs(node.edges) do
if not seen[e.to.key] then
local thisWay = longest_path(e.to, cost + e.cost, seen, level + 1)
if thisWay ~= nil and (max == nil or thisWay > max) then
max = thisWay
end
end
end
if max ~= nil then
--print(string.format("%sLongest path through %s is %d", string.rep(" ",level), node, max))
end
seen[node.key] = nil -- clean up
return max
end
local function part2(source)
local mgraph = parse(source, true)
--mgraph:print(true)
local start = mgraph:compress(true)
return longest_path(start, 0, {}, 0)
end
--[[ CLI ] ]--
local source = io.input("day23.input"):read("*a")
print('Longest path when wet:', part1(source))
print('Longest path when dry:', part2(source))
--[ [ 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('day23')
end)()
