![[PukiWiki]](image/pukiwiki.png "[PukiWiki]")
# Python 3 program for recursive binary search.
# Modifications needed for the older Python 2 are found in comments.
# Returns index of x in arr if present, else -1 def binary_search(arr, low, high, x):
# Check base case
if high >= low:
mid = (high + low) // 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 binary_search(arr, low, mid - 1, x)
# Else the element can only be present in right subarray
else:
return binary_search(arr, mid + 1, high, x)
else:
# Element is not present in the array
return -1
# Test array arr = [ 2, 3, 4, 10, 40 ] x = 10
# Function call result = binary_search(arr, 0, len(arr)-1, x)
if result != -1:
print("Element is present at index", str(result))
else:
print("Element is not present in array")
Output:
Element is present at index 3 Iterative:
filter_none edit play_arrow
brightness_4
# Iterative Binary Search Function
# It returns index of x in given array arr if present,
# else returns -1 def binary_search(arr, x):
low = 0
high = len(arr) - 1
mid = 0
while low <= high:
mid = (high + low) // 2
# Check if x is present at mid
if arr[mid] < x:
low = mid + 1
# If x is greater, ignore left half
elif arr[mid] > x:
high = mid - 1
# If x is smaller, ignore right half
else:
return mid
# If we reach here, then the element was not present
return -1
# Test array arr = [ 2, 3, 4, 10, 40 ] x = 10
# Function call result = binary_search(arr, x)
if result != -1:
print("Element is present at index", str(result))
else:
print("Element is not present in array")
Output:
Element is present at index 3
