Binary Search Tree

# Python3 Program for recursive binary search. 

# Returns index of x in arr if present, else -1 
def binarySearch (arr, l, r, x): 

	# Check base case 
	if r >= l: 

		mid = l + (r - l) // 2

		# If element is present at the middle itself 
		if arr[mid] == x: 
			return mid 
		
		# If element is smaller than mid, then it 
		# can only be present in left subarray 
		elif arr[mid] > x: 
			return binarySearch(arr, l, mid-1, x) 

		# Else the element can only be present 
		# in right subarray 
		else: 
			return binarySearch(arr, mid + 1, r, x) 

	else: 
		# Element is not present in the array 
		return -1

# Driver Code 
arr = [ 2, 3, 4, 10, 40 ] 
x = 10

# Function call 
result = binarySearch(arr, 0, len(arr)-1, x) 

if result != -1: 
	print ("Element is present at index % d" % result) 
else: 
	print ("Element is not present in array")