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Dutch national flag problem: Difference between revisions
→{{header|Lua}}: added Lua solution
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<pre>Start list: white blue red red red white blue red red white
Sorted: red red red red red white white white blue blue</pre>
=={{header|Lua}}==
The task seems to allow for some interpretation, so attempting to follow as literally as possible.
<lang lua>-- "1. Generate a randomized order of balls.."
math.randomseed(os.time())
N, balls, colors = 10, {}, { "red", "white", "blue" }
for i = 1, N do balls[i] = colors[math.random(#colors)] end
-- "..ensuring that they are not in the order of the Dutch national flag."
order = { red=1, white=2, blue=3 }
function issorted(t)
for i = 2, #t do
if order[t[i]] < order[t[i-1]] then return false end
end
return true
end
local function shuffle(t)
for i = #t, 2, -1 do
local j = math.random(i)
t[i], t[j] = t[j], t[i]
end
end
while issorted(balls) do shuffle(balls) end
print("RANDOM: "..table.concat(balls,","))
-- "2. Sort the balls in a way idiomatic to your language."
table.sort(balls, function(a, b) return order[a] < order[b] end)
-- "3. Check the sorted balls are in the order of the Dutch national flag."
print("SORTED: "..table.concat(balls,","))
print(issorted(balls) and "Properly sorted." or "IMPROPERLY SORTED!!")</lang>
{{out}}
<pre>RANDOM: white,white,blue,blue,red,red,blue,white,red,white
SORTED: red,red,red,white,white,white,white,blue,blue,blue
Properly sorted.</pre>
=={{header|M2000 Interpreter}}==
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