RosettaCodeData/Task/Last-letter-first-letter/Lua/last-letter-first-letter.lua
2023-07-01 13:44:08 -04:00

67 lines
2.2 KiB
Lua

-- BUILDING:
pokemon = [[
audino bagon baltoy banette bidoof braviary bronzor carracosta charmeleon
cresselia croagunk darmanitan deino emboar emolga exeggcute gabite
girafarig gulpin haxorus heatmor heatran ivysaur jellicent jumpluff kangaskhan
kricketune landorus ledyba loudred lumineon lunatone machamp magnezone mamoswine
nosepass petilil pidgeotto pikachu pinsir poliwrath poochyena porygon2
porygonz registeel relicanth remoraid rufflet sableye scolipede scrafty seaking
sealeo silcoon simisear snivy snorlax spoink starly tirtouga trapinch treecko
tyrogue vigoroth vulpix wailord wartortle whismur wingull yamask]]
words, inits, succs = {}, {}, {}
for word in pokemon:gmatch("%S+") do
table.insert(words, word)
local ch = word:sub(1,1)
inits[ch] = inits[ch] or {}
table.insert(inits[ch], word)
end
for _,word in pairs(words) do
succs[word] = {}
local ch = word:sub(-1,-1)
if inits[ch] then
for _,succ in pairs(inits[ch]) do
if succ~=word then
table.insert(succs[word],succ)
end
end
end
end
-- SEARCHING:
function expand(list, used, answer)
local word = list[#list]
for _,succ in ipairs(succs[word]) do
if not used[succ] then
used[succ] = true
list[#list+1] = succ
if #list == answer.len then
local perm = table.concat(list," ")
answer.perms[perm] = perm
answer.num = answer.num + 1
elseif #list > answer.len then
answer.len = #list
local perm = table.concat(list," ")
answer.perms = {[perm] = perm}
answer.num = 1
end
expand(list, used, answer)
list[#list] = nil
used[succ] = nil
end
end
end
answers = {}
for _,word in ipairs(words) do
local answer = { word=word, len=0, num=0, perms={} }
answers[#answers+1] = answer
expand({word}, {[word]=true}, answer)
end
-- REPORTING:
table.sort(answers, function(a,b) return a.len<b.len or (a.len==b.len and a.word<b.word) end)
print("first word length count example")
print("---------- ------ ----- -------...")
for _,answer in pairs(answers) do
local perm = next(answer.perms) or ""
print(string.format("%10s %6d %5d %s", answer.word, answer.len, answer.num, perm))
end