Python Algorithms

binary_searh.py

# Iterative Binary Search Function 
def binary_search(list1, n):  
    low = 0  
    high = len(list1) - 1  
    mid = 0  
  
    while low <= high:  
        # for get integer result   
        mid = (high + low) // 2  
  
        # Check if n is present at mid   
        if list1[mid] < n:  
            low = mid + 1  
  
        # If n is greater, compare to the right of mid   
        elif list1[mid] > n:  
            high = mid - 1  
  
        # If n is smaller, compared to the left of mid  
        else:  
            return mid  
  
            # element was not present in the list, return -1  
    return -1  
  
  
# Initial list1  
list1 = [12, 24, 32, 39, 45, 50, 54]  
n = 45  
  
# Function call   
result = binary_search(list1, n)  
  
if result != -1:  
    print("Element is present at index", str(result))  
else:  
    print("Element is not present in list1")  

recursive_binary_search.py

# recursive binary search.  
def binary_search(list1, low, high, n):   
  
   # Check base case for the recursive function  
   if low <= high:  
  
      mid = (low + high) // 2  
  
      # If element is available at the middle itself then return the its index  
      if list1[mid] == n:   
         return mid   
  
      # If the element is smaller than mid value, then search moves  
      # left sublist1  
      elif list1[mid] > n:   
         return binary_search(list1, low, mid - 1, n)   
  
      # Else the search moves to the right sublist1  
      else:   
         return binary_search(list1, mid + 1, high, n)   
  
   else:   
      # Element is not available in the list1  
      return -1  
  
# Test list1ay   
list1 = [12, 24, 32, 39, 45, 50, 54]  
n = 32  
  
# Function call   
res = binary_search(list1, 0, len(list1)-1, n)   
  
if res != -1:   
   print("Element is present at index", str(res))  
else:   
   print("Element is not present in list1")