# Python program to implement interpolation search
#  using iteration approach
def interpolationSearch(arr, n, x):

	# Find indexes of two corners
	low = 0
	high = (n - 1)

	# Since array is sorted, an element present
	# in array must be in range defined by corner
	while low <= high and x >= arr[low] and x <= arr[high]:
		if low == high:
			if arr[low] == x:
				return low;
			return -1;

		# Probing the position with keeping
		# uniform distribution in mind.
		pos = int(low + (((float(high - low)/( arr[high] - arr[low])) * (x - arr[low]))))

		# Condition of target found
		if arr[pos] == x:
			return pos

		# If x is larger, x is in upper part
		if arr[pos] < x:
			low = pos + 1;

		# If x is smaller, x is in lower part
		else:
			high = pos - 1;
	
	return -1

# Main function
if __name__ == "__main__":
	# Array of items on whighch search will
	# be conducted.
	arr = [10, 12, 13, 16, 18, 19, 20, 21,
		22, 23, 24, 33, 35, 42, 47]
	n = len(arr)

	x = 18 # Element to be searched
	index = interpolationSearch(arr, n, x)

	# If element was found
	if index != -1:
		print ("Element found at index",index)
	else:
		print ("Element not found")