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Summarize and say sequence: Difference between revisions
Added Lua version
SqrtNegInf (talk | contribs) m (→{{header|Perl 6}}: various fixes) |
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=={{header|Lua}}==
Runs in about nine seconds under LuaJIT. Uses memoisation via the global table 'nextTerm'.
<lang lua>-- Return the next term in the self-referential sequence
function findNext (nStr)
local nTab, outStr, pos, count = {}, "", 1, 1
for i = 1, #nStr do nTab[i] = nStr:sub(i, i) end
table.sort(nTab, function (a, b) return a > b end)
while pos <= #nTab do
if nTab[pos] == nTab[pos + 1] then
count = count + 1
else
outStr = outStr .. count .. nTab[pos]
count = 1
end
pos = pos + 1
end
return outStr
end
-- Return boolean indicating whether table t contains string s
function contains (t, s)
for k, v in pairs(t) do
if v == s then return true end
end
return false
end
-- Return the sequence generated by the given seed term
function buildSeq (term)
local sequence = {}
repeat
table.insert(sequence, term)
if not nextTerm[term] then nextTerm[term] = findNext(term) end
term = nextTerm[term]
until contains(sequence, term)
return sequence
end
-- Main procedure
nextTerm = {}
local highest, seq, hiSeq = 0
for i = 1, 10^6 do
seq = buildSeq(tostring(i))
if #seq > highest then
highest = #seq
hiSeq = {seq}
elseif #seq == highest then
table.insert(hiSeq, seq)
end
end
io.write("Seed values: ")
for _, v in pairs(hiSeq) do io.write(v[1] .. " ") end
print("\n\nIterations: " .. highest)
print("\nSample sequence:")
for _, v in pairs(hiSeq[1]) do print(v) end</lang>
{{out}}
<pre>Seed values: 9009 9090 9900
Iterations: 21
Sample sequence:
9009
2920
192210
19222110
19323110
1923123110
1923224110
191413323110
191433125110
19151423125110
19251413226110
1916151413325110
1916251423127110
191716151413326110
191726151423128110
19181716151413327110
19182716151423129110
29181716151413328110
19281716151423228110
19281716151413427110
19182716152413228110</pre>
=={{header|Mathematica}}==
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