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Data Structures and Algorithms with Python – Third Edition

Hands-On Data-Structures-and-Algorithms-with-Python-Third-Edition-published-by-Packt

Hands-On Data Structures and Algorithms with Python – Third Edition

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hands-on-data-structures-and-algorithms-with-python-third-edition's Issues

Wrong comparing

Hands-On-Data-Structures-and-Algorithms-with-Python-Third-Edition/Chapter04/append_at_any_location_singly_linkedlist.py

Line 36 in f234dae

elif index == index:

it should be compared with count==index, we check whether we have reached the required index position by comparing the value of count and index. If both values are equal, we add a new node in between nodes indicated by prev and current and update the pointers accordingly.

Chapter 5 pop function wrong

In chapter 5 you recreate pop(). The code de-increment top by 1, then changing top value to 0. It needs to be switched like so.

def pop():
global top
if top == -1:
print("Stack Underflow")
else:
data[top] = 0
top = top - 1
return data[top+1]

(formatting is not being kept sorry for sloppy indents)

Check index==1, instead of count==1

Hands-On-Data-Structures-and-Algorithms-with-Python-Third-Edition/Chapter04/append_at_any_location_singly_linkedlist.py

Line 31 in f234dae

if count == 1:

Firstly, we check whether the index position is 1, not count ==1

chapter 4 linked list code snippet in the book is wrong

class SinglyLinkedList:
    def __init__ (self):
        self.tail = None
        self.head = None
        self.size = 0
    def append_at_a_location(self, data, index): 
        current = self.head 
        prev = self.head 
        node = Node(data)
        count = 1
        while current:
            if count == 1:        
                node.next = current
                self.head = node
                print(count)
                return
            elif index == index:
                node.next = current 
                prev.next = node
                return
            count += 1
            prev = current
            current = current.next
        if count < index:
            print("The list has less number of elements")

this code snippet can't demo the concept of inserting new element at a given index. instead, it always insert the new element at the beginning of the list.

please correctify this error.

thanks

ZeroDivisionError is raised in interpolation search

With the current implementation of interpolation search, ZeroDivisionError raises.

Here is an example:

def nearest_mid(input_list, low_index, upper_index, search_value):
    mid = low_index + (
        (upper_index - low_index) / (input_list[upper_index] - input_list[low_index])
    ) * (search_value - input_list[low_index])
    return int(mid)


def interpolation_search(ordered_list, search_value):
    low_index = 0
    upper_index = len(ordered_list) - 1
    while low_index <= upper_index:
        mid_point = nearest_mid(ordered_list, low_index, upper_index, search_value)
        if mid_point > upper_index or mid_point < low_index:
            return None
        if ordered_list[mid_point] == search_value:
            return mid_point
        if search_value > ordered_list[mid_point]:
            low_index = mid_point + 1
        else:
            upper_index = mid_point - 1
    if low_index > upper_index:
        return None


list1 = [44, 60, 75, 100, 120, 230, 250]
print(interpolation_search(list1, 231))

output:

Traceback (most recent call last):
  File "", line 26, in <module>
    print(interpolation_search(list1, 231))
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "", line 12, in interpolation_search
    mid_point = nearest_mid(ordered_list, low_index, upper_index, search_value)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "", line 3, in nearest_mid
    (upper_index - low_index) / (input_list[upper_index] - input_list[low_index])
    ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ZeroDivisionError: division by zero