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leighhalliday/output.txt

Created May 9, 2015 18:45
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Recursive "Carnac" solution in Ruby
Raw
output.txt
1 + 2 + 3 - 4 + 5 + 6 + 78 + 9
1 + 2 + 34 - 5 + 67 - 8 + 9
1 + 23 - 4 + 5 + 6 + 78 - 9
1 + 23 - 4 + 56 + 7 + 8 + 9
12 + 3 + 4 + 5 - 6 - 7 + 89
12 + 3 - 4 + 5 + 67 + 8 + 9
12 - 3 - 4 + 5 - 6 + 7 + 89
123 + 4 - 5 + 67 - 89
123 - 4 - 5 - 6 - 7 + 8 - 9
123 + 45 - 67 + 8 - 9
123 - 45 - 67 + 89
Raw
solutions.rb
def solutions(acc, rem)
if rem.size == 0
if sum_array_with_operators(acc.reverse) == 100
puts acc.join(" ")
end
else
head, *tail = *rem
if acc.size == 0
# get things going
solutions([head], tail)
else
# +
solutions(acc + [:+, head], tail)
# -
solutions(acc + [:-, head], tail)
end
# concatenate
if tail.size > 0
tail[0] = (head * 10) + tail[0]
solutions(acc, tail)
end
end
end
# Arrives like this: [1, :+, 2, :-, 3, :+, 5]
def sum_array_with_operators(arr)
if arr.size == 1
arr[0]
else
num, operator, *tail = *arr
sum_array_with_operators(tail).send(operator, num)
end
end
solutions([], (1..9).to_a)
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