Balanced brackets
editable example
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ghul
use IO.Std.write_line
use Ghul.Pipes
balanced(brackets: string) -> bool => (
let level mut = 0
let matched = for bracket in brackets do
if bracket == ']' /\ level == 0 then break false fi
level = level + (if bracket == '[' then 1 else -1 fi)
od
matched ?? (level == 0)
)
arrangements(opens: int, closes: int) -> Pipe[string] is
if opens == 0 /\ closes == 0 then
yield ""
else
if opens > 0 then
yield in arrangements(opens - 1, closes)
|> map(rest => "[{rest}")
fi
if closes > 0 then
yield in arrangements(opens, closes - 1)
|> map(rest => "]{rest}")
fi
fi
si
for pairs in 0::3 do
for brackets in arrangements(pairs, pairs) do
let verdict = if balanced(brackets) then "OK" else "NOT OK" fi
write_line("{brackets,6} {verdict}")
od
od