find-number-in-sorted-rotated.rb

a = (1..100).to_a.rotate 7
x = 2
steps = 0
n = 0
l = 0
r = a.length

while true do
  steps+=1

  m = (r-l+1) / 2
  n = l + m
  
  break if a[n] == x
  (n = l; break) if a[l] == x
  (n = r; break) if a[r] == x

  
  if (a[l] < a[n]) && (a[l] < x && a[n] > x) 
    r = n
  elsif (a[l] > a[n]) && (a[l] < x || x < a[n])
    r = n
  else 
    l = n
  end
  
  break if steps > 20
end

puts "#{x} is N #{n} (start from 0) in"
puts a.inspect
puts "found in #{steps} steps"