Category Archives: 99 Python Problems

breakfast = ["Sausage", "Eggs", "Beans", "Bacon", "Tomatoes", "Mushrooms"]
palindromic = ["Sausage", "Eggs", "Beans", "Beans", "Eggs", "Sausage"]
nums = [1,1,3,3,3,2,2,2,1,1,1,1,4,4,4,4]
letters = ['a', 'a', 'a', 'a', 'b', 'c', 'c', 'a', 'a', 'd', 'e', 'e', 'e', 'e']

def print_list(list):
    for item in list:
        print(item)

def last_element(list):
    return (list[-1])

def last_but_one(list):
    return (list[-2])

# Using reversed function
def my_reverse(list):
    new_list = []
    for item in reversed(list):
        new_list.append(item)
    return new_list

# Using for loop
def my_reverse2(list):
    new_list = []
    for i in range (len(list)-1, -1, -1):
        new_list.append(list[i])
    return new_list

# Using list comprehension
def my_reverse3(list): 
    return [item for item in reversed(list)] 

# Using slicing
def my_reverse4(list): 
    return list[::-1]
  
    
def is_palindrome(list):
    if list == my_reverse(list):
        return True
    else:
        return False

def compress(list):
    new_list = []
    last_item = list[0] + 1 # so first number is different to itself
    for num in list:
        if num != last_item:
            new_list.append(num)
        last_item = num
    return new_list

def pack(list):
    pack_list = []
    last_item = list[0]
    word = ""
    for item in list:
        if item == last_item:
            word = word + item
        else:
            pack_list.append(word)
            word = item
        last_item = item
    pack_list.append(word)
    return pack_list

3.1 Print List

Write a function that prints out a list, one element per line

3.1.1 Example

 1: breakfast = ["Sausage", "Eggs", "Beans", "Bacon", "Tomatoes", "Mushrooms"]
 2: 
 3: print_list(breakfast)
 4:  *** Output ***
 5: Sausage
 6: Eggs
 7: Beans
 8: Bacon
 9: Tomatoes
10: Mushrooms

3.2 Last Element of Array

Write a function that returns the last element of a string array

3.2.1 Example

1: breakfast = ["Sausage", "Eggs", "Beans", "Bacon", "Tomatoes", "Mushrooms"]
2: 
3: print(last_element(breakfast));
4:  *** Output ***
5: Mushrooms

3.3 Last But One Element of Array

Write a function that returns the last but one element of a string array

3.3.1 Example

1: breakfast = ["Sausage", "Eggs", "Beans", "Bacon", "Tomatoes", "Mushrooms"]
2: 
3: print(last_but_one(breakfast));
4:  *** Output ***
5: Tomatoes

3.4 Reverse a list, leaving original intact

Return a list in reverse order, while leaving the original list intact.

3.4.1 Example

 1: breakfast = ["Sausage", "Eggs", "Beans", "Bacon", "Tomatoes", "Mushrooms"]
 2: 
 3: print(my_reverse(breakfast))
 4: print(breakfast)
 5:  *** Output ***
 6: : Mushrooms
 7: : Tomatoes
 8: : Bacon
 9: : Beans
10: : Eggs
11: : Sausage
12: : Sausage
13: : Eggs
14: : Beans
15: : Bacon
16: : Tomatoes
17: : Mushrooms

3.5 Palindromic lists

Write a function that tests to see if a list is palindromic, i.e. the elements are the same when reversed.

3.5.1 Example

1: palindromic = ["Sausage", "Eggs", "Beans", "Beans", "Eggs", "Sausage"]
2: breakfast = ["Sausage", "Eggs", "Beans", "Bacon", "Tomatoes", "Mushrooms"]
3: 
4: print(is_palindrome(palindromic))
5: print(is_palindrome(breakfast))
6:  *** Output ***
7: True
8: False

3.6 Consecutive Duplicates

Write a function to print out list of integers with consecutive duplicates eliminated

1: nums = [1,1,3,3,3,2,2,2,1,1,1,1,4,4,4,4]
2: 
3: compress(nums)
4:  *** Output ***
5: : 1
6: : 3
7: : 2
8: : 1
9: : 4

3.7 Pack Duplicates

Pack consecutive duplicates of a char list into Strings

1: letters = ['a', 'a', 'a', 'a', 'b', 'c', 'c', 'a', 'a', 'd', 'e', 'e', 'e', 'e']
2: 
3: pack(letters)
4:  *** Output ***
5: : aaaa, b, cc, aa, d, eeee

2 Loop Solutions

 1: def oneToTen():
 2:         for i in range(1,11):
 3:                 print(i)
 4: 
 5: def oneToTenAcross():
 6:       print("|", end="")
 7:         for i in range(1,11):
 8:                 print(i,"|",end="")
 9: 
10: def oddNumbers():
11:         for i in range(1,21,2):
12:                 print(i)
13: 
14: def squares():
15:         for i in range(1,11):
16:                 print(i*i)
17: 
18: def random4():
19:         for i in range(1,5):
20:                 print(random.randint(1,10))
21: 
22: def even(n):
23:         for i in range(1,n+1):
24: 
25: 
26: def powers(n):
27:         for i in range(1,n+1):
28:                 print(2**i)
29: 
30: def triangle():
31:         for i in range(1,6):
32:                 for j in range(1,i+1):
33:                         print("*", end = "")
34:                 print()
35: 
36: def areWeThereYet():
37:         s = "no"
38:         while (s != "yes"):
39:                 s = input("Are we there yet?")
40:         print ("Good!")
41: 
42: 
43: def tableSquare():
44:         for i in range(1,5):
45:                 for j in range (1, 5):
46:                         print("|",i*j, "\t", end = "")
47:                 print("|")
48: 
49: def tableSquares(n):
50:         for i in range(1,n+1):
51:                 for j in range (1, n+1):
52:                         print("|",i*j, "\t", end = "")
53:                 print("|")

Write functions to solve all of the questions. Here are two example questions and their solutions. Notice that the first function prints a value, the second function returns a value.

hello("Kim")
 *** Output ***
Hello Kim

print(average(3,4));
 *** Output ***
3.5

1: def hello(s):
2:     print("Hello ",s)
3: 
4: def average(i,j):
5:     return (i+j)/2
6: 
7: hello("Kim")
8: print(average(3,5))