/
karate.cr
48 lines (40 loc) · 1.16 KB
/
karate.cr
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require "./karate/*"
class Karate
getter :sorted_array
@sorted_array : Array(Int32)
@default_range : Range(Int32, Int32)
def initialize(array)
@empty_range = (0..-1)
@sorted_array = array.sort
@default_range = (0..(@sorted_array.size-1))
end
def chop(guess)
search_range = @default_range
while search_range.size > 0
mdx = 0
mdx = middle_of_range(search_range)
middle_item = @sorted_array[mdx]
if guess == middle_item
return mdx
elsif guess < middle_item
search_range = left_range(mdx)
else
search_range = right_range(mdx, search_range.max)
end
end
-1 # not found
end
def middle_of_range(range = @default_range)
if range.size>0
range.min + (range.max-range.min) / 2
else
-1 # never gonna happen
end
end
def left_range(excluded_index = middle_of_range())
excluded_index ? 0..(excluded_index-1) : @empty_range
end
def right_range(excluded_index = middle_of_range(), max = @default_range.max)
excluded_index ? (excluded_index+1)..max : @empty_range
end
end