http://www.geeksforgeeks.org/search-an-element-in-a-sorted-and-pivoted-array/

search-an-element-in-a-sorted-and-pivoted-array

#ex array
a = [3,4,5,1,2]

pivot = -1
(0..a.length-1).each do |i|
    if a[i] > a[i+1] 
      pivot = i+1
      break
    end
end

def bsearch(a, i, j, n)
    mid = (i + j)/2
    if i == j and n != a[mid]
        return -1
    end
    if n == a[mid]
        return mid
    elsif n < a[mid]
        return bsearch(a, i, mid, n)
    elsif n > a[mid]
        return bsearch(a, mid+1, j, n)
    end
end

#Client code
x = bsearch(a[0..pivot-1], 0, pivot-1, 2)
y = bsearch(a[pivot..a.length-1], 0, a.length-1-pivot, 2)

if x != -1
    puts "Found #{x}"
elsif y != -1
    puts "Found #{y+pivot}"
else
    put "NOT Found"
end