# Solutions for Binary Search

• ``````# Python3 Program for recursive binary search.
import json
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

def solve(lst,b):
n=len(lst)
result=binarySearch(lst, 0, n-1, b)
if result != -1:
return result
else:
return -1
``````
• ``````# Python3 Program for recursive binary search.
import json
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