Question

Python Homework: -

NOTE - Must not use built-in functions (other than the range() function), slice expressions, list methods (other than the append() method) or string methods in your solution.

Write a function called reverse(my_list, number=-1)

that takes a list and a number as parameters. The function returns a copy of the list with the first number of items reversed.

Conditions: -

The number parameter must be a default argument.
-      If the default argument for number is given in the function call, only the first number of items are reversed.
-      If the default argument for number is not provided in the function call, then the entire list is reversed. Check for the number value exceeding the list bounds (i.e. is greater than the length of the list).
-    If the number value exceeds the list bounds, then make the number value the length of the list.
-    If the number value entered is less than two, then return a copy of the list with no items reversed.

You must use a loop(s) in your solution. You may make use of the list_name.append(item) method in order to build the new list. You must not use built-in functions (other than the range() function), slice expressions, list methods (other than the append() method) or string methods in your solution.

Answer 1

Copy the below code in a .py file :-

#!/usr/bin/env python
# coding: utf-8

def reverse(my_list, number=-1):
lengthOfList =0
  
# Find the length of the list ( we annot use a list function)
for item in my_list:
lengthOfList = lengthOfList +1
# The list that represents the reversed List
reversedList = []
  
# If defualt argument was passed, reverse only first element
if number == -1:
# Copy last element first
reversedList.append(my_list[-1])
# Copy rest of list except the last parameter
for index in range(1,lengthOfList-1):
reversedList.append(my_list[index])
# copy the first element in the last
reversedList.append(my_list[0])
# If the no of elements > length of list
elif number >lengthOfList:
# Set the no of elements as list bound
number = lengthOfList
# If number value is less than 2
if number <=2:
# Copy the same list
for index in range(0,lengthOfList):
reversedList.append(my_list[index])
else:
# Other wise reverse the whole list
for index in range(lengthOfList-1, -1, -1):   
reversedList.append(my_list[index])
# If number value is less than 2
elif number <=2:
# Copy the same list
for index in range(0,lengthOfList):
reversedList.append(my_list[index])
# In all other cases reverse the entire list
else:
# Other wise reverse the whole list
for index in range(lengthOfList-1, -1, -1):   
reversedList.append(my_list[index])   

return reversedList

def main():
listOfNumbers =[1,2, 3,4, 5,6]   
print(listOfNumbers)
print("Reverse with no number parameters")   
print(reverse(listOfNumbers))
print("Reverse with number parameter value out of bounds")   
print(reverse(listOfNumbers,9))   
print("Reverse with number parameter value <=2")   
print(reverse(listOfNumbers,1))
print("Reverse with number parameter value 4")   
print(reverse(listOfNumbers,4))
  

if __name__== "__main__":
main()

Code Screenshot for indentation

Sample Output