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#!/usr/bin/env lua
local t2 = {}
function t2.interleave_string(a, b, c)
if a:len() == 0 then return b == c end
if b:len() == 0 then return a == c end
if c:len() ~= a:len() + b:len() then return end
-- get heads (1st char) and tails (the rest)
local ah, at = a:match("^(%a)(%a*)$")
local bh, bt = b:match("^(%a)(%a*)$")
local ch, ct = c:match("^(%a)(%a*)$")
return ((ah == ch) and t2.interleave_string(at, b, ct))
or ((bh == ch) and t2.interleave_string(a, bt, ct))
end
function t2.run(args)
if #args ~= 3 then
io.stderr:write("error: must supply three strings\n")
os.exit(2)
end
local a, b, c = table.unpack(args, 1, 3)
local result = t2.interleave_string(a, b, c)
if result then print(1) else print(0) end
end
return t2
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