Question

Python Mutable Sequences Implement a function reverse that takes a list as an argument and reverses...

Python

Mutable Sequences

Implement a function reverse that takes a list as an argument and reverses the list. You should mutate the original list, without creating any new lists. Do NOT return anything. Do not use any built-in list functions such as reverse().

def reverse(lst):

   """Reverses lst in place (i.e. doesn't create new lists).

    >>> L = [1, 2, 3, 4]

    >>> reverse(L)

    >>> L

    [4, 3, 2, 1]

    """

Homework Answers

Answer #1
def reverse(lst):
    """Reverses lst in place (i.e. doesn't create new lists).
     >>> L = [1, 2, 3, 4]
     >>> reverse(L)
     >>> L
     [4, 3, 2, 1]
     """
    for i in range(len(lst) // 2):
        lst[i], lst[len(lst) - i - 1] = lst[len(lst) - i - 1], lst[i]


# Testing the function here. ignore/remove the code below if not required
L = [1, 2, 3, 4]
print(L)
reverse(L)
print(L)
L = [1, 2, 3, 4, 5]
print(L)
reverse(L)
print(L)

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
python 3 For this exercise you are to implement the function poly_iter in the array-backed list...
python 3 For this exercise you are to implement the function poly_iter in the array-backed list class, which, when called with positive integer parameters a, b, c, returns an iterator over the values in the underlying list at indexes a*i2+b*i+c, for i=0, 1, 2, ... E.g., given an array-backed list lst containing the elements [0, 1, 2, 3, 4, ..., 98, 99], the following code: for x in lst.poly_iter(2, 3, 4): print(x) will produce the output: 4 9 18 31...
Implement function reverse that takes a 2D list (a list of list of integers) and returns...
Implement function reverse that takes a 2D list (a list of list of integers) and returns a new 2D list where the items in each row are in reverse order. You maynot use slicing. You may not modify the input list. The returned list should be completely new in memory – no aliases with the input 2D list. From list methods, you may use only the .append(). Examples: reverse([[1,2,3],[4,5,6]])       ->    [[3,2,1],[6,5,4]] reverse([[1,2],[3,4],[5,6]])     ->    [[2,1],[4,3][6,5]] True False In python please
Implement function swap that takes a 2D list (a list of list of integers) and modifies...
Implement function swap that takes a 2D list (a list of list of integers) and modifies it in-place by swapping the first element in each row with the last element in that row. The return value is None. You may not use slicing. You maynot use any list method like append, insert, etc. Modification must be in-place, you may not move the list itself or any of its sublists to a new memory location. Examples: reverse([[1,2,3],[4,5,6]])        ->    [[3,2,1],[6,5,4]] reverse([[1,2,3,4],[5,6,7,8]])    ->    [[4,2,3,1],[8,6,7,5]]...
In Python, implement a function that takes in two sorted lists and merges them into one...
In Python, implement a function that takes in two sorted lists and merges them into one list, the new list must be sorted. The function MUST run in O(m+n), where m is the length of list 1 and n the length of list 2. In other words, the function cannot do more than one pass on list 1 and list 2.
Problem 2: Python 3 Implement a function called gee_whiz that does the following: given argument n,...
Problem 2: Python 3 Implement a function called gee_whiz that does the following: given argument n, a positive integer, it returns a list of n tuples corresponding to the numbers 1 through n (both inclusive): the tuple for the number k consists of k as the first component, and exactly one of the following strings as the second: • the string 'two!' if k is divisible by 2 • the string 'three!' if k is divisible by 3 • the...
Python 3 Implement the function invert_and_merge, which takes any number of input dictionaries via a star...
Python 3 Implement the function invert_and_merge, which takes any number of input dictionaries via a star parameter, and inverts and merges them into a single result dictionary. When inverting a dictionary, the keys and values are flipped, so that each value maps to a set containing the corresponding key(s) in the original dictionary. When merging the inverted dictionaries, sets corresponding to the same key are combined. Examples: invert_and_merge({'a': 1, 'b': 2, 'c': 1, 'd': 1, 'e': 2}) should return {1:...
Please write a python code for the following. Use dictionaries and list comprehensions to implement the...
Please write a python code for the following. Use dictionaries and list comprehensions to implement the functions defined below. You are expected to re-use these functions in implementing other functions in the file. Include a triple-quoted string at the bottom displaying your output. Here is the starter outline for the homework: d. def count_words(text): """ Count the number of words in text """ return 0 e. def words_per_sentence(text): return 0.0 f. def word_count(text, punctuation=".,?;"): """ Return a dictionary of word:count...
Python 3 Implement the function condense, which takes a "passage" (a string containing multiple sentences separated...
Python 3 Implement the function condense, which takes a "passage" (a string containing multiple sentences separated by the '\n' character), and returns a condensed version of that passage based on the following logic: the frequency with which each word appears in the entire passage is computed a score for each sentence in the passage is computed by summing the frequency of each word in the sentence the sentences with the top 3 scores (we assume there are no ties) are...
(For Python) Evaluating Postfix Arithmetic Expressions. In this project you are to implement a Postfix Expression...
(For Python) Evaluating Postfix Arithmetic Expressions. In this project you are to implement a Postfix Expression Evaluator as described in section 7-3b of the book. The program should ask the user for a string that contains a Postfix Expression. It should then use the string's split function to create a list with each token in the expression stored as items in the list. Now, using either the stack classes from 7.2 or using the simulated stack functionality available in a...
Write the algorithm for this program using the C++ language (not python or java). The explanation...
Write the algorithm for this program using the C++ language (not python or java). The explanation needs to be at least 250 words. Explain everything throughly step by step. While there is a built-in pop_back function in the vector class, there is no built-in pop_front function. Suppose a program needs a pop_front function that will remove the first element from the vector. For example, if the original vector is [1, 2, 3, 4, 5], then after passing in this vector...
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT