List Puzzles

There are 7 List puzzles in this lab. There are a series of print statements in the main method of which you need to create some simple tests.

Same End

Given 2 arrays (lists) of ints, a and b, return True if they have the same first element or they have the same last element. Both arrays will be length 1 or more.

same_end([1, 2, 3], [7, 3]) → True
same_end([1, 2, 3], [7, 3, 2]) → False
same_end([1, 2, 3], [1, 3]) → True

def same_end(list_a, list_b):
    # ++ Your code here ++

    return "a boolean"

List Sum

Given an array (list) of ints, return the sum of all the elements. You must use a loop and may not use the sum() function

list_sum([1, 2, 3]) → 6
list_sum([5, 11, 2]) → 18
list_sum([7, 0, 0]) → 7

def list_sum(num_list):
    # ++ Your code here ++

    return "the sum"

Backwards

Given an array (list), return an array with the elements in backwards order You must use a loop and may not use the reverse() function

backwards([1, 2, 3]) → [3, 2, 1]
backwards([5, 11, 9, 8]) → [8, 9, 11, 5]
backwards([7, 0, "zero"]) → ["zero", 0, 7]
backwards(["pig", "horse", "cat"]) → ["cat", "horse", "pig"]

def backwards(list):
    # ++ Your code here ++

    return "the array backwards"

Average

Given an array (list) of numbers, return the average of the array

average([1, 2, 3]) → 2
average([5, 11, 2]) → 6
average([7, 0, 1]) → 2.6666666667

def average(num_list):
    # ++ Your code here ++

    return "the average"

Count Evens

Return the number of even ints in the given array (should return an int). Note: the % "mod" operator computes the remainder, e.g. 5 % 2 is 1.

count_evens([2, 1, 2, 3, 4]) → 3
count_evens([2, 2, 0]) → 3
count_evens([1, 3, 5]) → 0

def count_evens(list):
    # +++ Your code here +++

    return "number of evens"

Biggest Difference

Given an array of ints with a length 1 or more, return the difference between the largest and smallest values in the array (should return an int).

big_diff([10, 3, 5, 6]) → 7
big_diff([7, 2, 10, 9]) → 8
big_diff([-20, -10, -7, -2]) → 18

def big_diff(list):
    # +++ Your code here +++

    return "biggest difference"

Centered Average

Return the "centered" average of an array of ints, which we'll say is the mean average of the values, except ignoring the largest and smallest values in the array. If there are multiple copies of the smallest value, ignore just one copy, and likewise for the largest value. You may assume that the array is length 3 or more. (should return a float)

centered_average([1, 2, 3, 4, 100]) → 3
centered_average([1, 1, 5, 10, 8, 7]) → 5.25
centered_average([-10, -4, -2, -4, -2, 1]) → -3

def centered_average():
    # +++ your code here +++

    return "centered average"