Python problems and solutions

Exercise 2: Print the sum of the current number and the previous number

Write a program to iterate the first 10 numbers and in each iteration, print the sum of the current and previous number.

Expected Output:

Printing current and previous number sum in a range(10) Current Number 0 Previous Number 0 Sum: 0 Current Number 1 Previous Number 0 Sum: 1 Current Number 2 Previous Number 1 Sum: 3 Current Number 3 Previous Number 2 Sum: 5 Current Number 4 Previous Number 3 Sum: 7 Current Number 5 Previous Number 4 Sum: 9 Current Number 6 Previous Number 5 Sum: 11 Current Number 7 Previous Number 6 Sum: 13 Current Number 8 Previous Number 7 Sum: 15 Current Number 9 Previous Number 8 Sum: 17

Reference article for help:

• Create a variable called previous_num and assign it to 0
• Iterate the first 10 numbers one by one using for loop and range() function
• Next, display the current number ( i ), previous number, and the addition of both numbers in each iteration of the loop. At last, change the value previous number to current number ( previous_num = i ).

print("Printing current and previous number and their sum in a range(10)") previous_num = 0 # loop from 1 to 10 for i in range(1, 11): x_sum = previous_num + i print("Current Number", i, "Previous Number ", previous_num, " Sum: ", x_sum) # modify previous number # set it to the current number previous_num = i

Exercise 3: Print characters from a string that are present at an even index number

Write a program to accept a string from the user and display characters that are present at an even index number.

For example, str = "pynative" so you should display ‘p’, ‘n’, ‘t’, ‘v’.

Expected Output:

Orginal String is pynative Printing only even index chars p n t v

Reference article for help: Python Input and Output

• Use Python input() function to accept a string from a user.
• Calculate the length of string using the len() function
• Next, iterate each character of a string using for loop and range() function.
• Use start = 0 , stop = len(s)-1, and step =2 . the step is 2 because we want only even index numbers
• in each iteration of a loop, use s[i] to print character present at current even index number

# accept input string from a user word = input('Enter word ') print("Original String:", word) # get the length of a string size = len(word) # iterate a each character of a string # start: 0 to start with first character # stop: size-1 because index starts with 0 # step: 2 to get the characters present at even index like 0, 2, 4 print("Printing only even index chars") for i in range(0, size - 1, 2): print("index[", i, "]", word[i])

Solution 2: Using list slicing

# accept input string from a user word = input('Enter word ') print("Original String:", word) # using list slicing # convert string to list # pick only even index chars x = list(word) for i in x[0::2]: print(i) 

Exercise 4: Remove first n characters from a string

Write a program to remove characters from a string starting from zero up to n and return a new string.

• remove_chars("pynative", 4) so output must be tive . Here we need to remove first four characters from a string.
• remove_chars("pynative", 2) so output must be native . Here we need to remove first two characters from a string.

Note: n must be less than the length of the string.

Use string slicing to get the substring. For example, to remove the first four characters and the remeaning use s[4:] .

def remove_chars(word, n): print('Original string:', word) x = word[n:] return x print("Removing characters from a string") print(remove_chars("pynative", 4)) print(remove_chars("pynative", 2)) 

Exercise 5: Check if the first and last number of a list is the same

Write a function to return True if the first and last number of a given list is same. If numbers are different then return False .

numbers_x = [10, 20, 30, 40, 10] numbers_y = [75, 65, 35, 75, 30]

Expected Output:

Given list: [10, 20, 30, 40, 10] result is True numbers_y = [75, 65, 35, 75, 30] result is False

def first_last_same(numberList): print("Given list:", numberList) first_num = numberList[0] last_num = numberList[-1] if first_num == last_num: return True else: return False numbers_x = [10, 20, 30, 40, 10] print("result is", first_last_same(numbers_x)) numbers_y = [75, 65, 35, 75, 30] print("result is", first_last_same(numbers_y)) 

Exercise 6: Display numbers divisible by 5 from a list

Iterate the given list of numbers and print only those numbers which are divisible by 5

Expected Output:

Given list is [10, 20, 33, 46, 55] Divisible by 5 10 20 55

num_list = [10, 20, 33, 46, 55] print("Given list:", num_list) print('Divisible by 5:') for num in num_list: if num % 5 == 0: print(num) 

Also, try to solve Python list Exercise

Exercise 7: Return the count of a given substring from a string

Write a program to find how many times substring “Emma” appears in the given string.

str_x = "Emma is good developer. Emma is a writer"

Expected Output:

Solution 1: Use the count() method

str_x = "Emma is good developer. Emma is a writer" # use count method of a str class cnt = str_x.count("Emma") print(cnt) 

Solution 2: Without string method

def count_emma(statement): print("Given String: ", statement) count = 0 for i in range(len(statement) - 1): count += statement[i: i + 4] == 'Emma' return count count = count_emma("Emma is good developer. Emma is a writer") print("Emma appeared ", count, "times")

Exercise 8: Print the following pattern

1 2 2 3 3 3 4 4 4 4 5 5 5 5 5

for num in range(10): for i in range(num): print (num, end=" ") #print number # new line after each row to display pattern correctly print("\n")

Exercise 9: Check Palindrome Number

Write a program to check if the given number is a palindrome number.

A palindrome number is a number that is same after reverse. For example 545, is the palindrome numbers

Expected Output:

original number 121 Yes. given number is palindrome number original number 125 No. given number is not palindrome number

• Reverse the given number and save it in a different variable
• Use the if condition to check if the original number and reverse number are the same. If yes, return True .

def palindrome(number): print("original number", number) original_num = number # reverse the given number reverse_num = 0 while number > 0: reminder = number % 10 reverse_num = (reverse_num * 10) + reminder number = number // 10 # check numbers if original_num == reverse_num: print("Given number palindrome") else: print("Given number is not palindrome") palindrome(121) palindrome(125) 

Exercise 10: Create a new list from a two list using the following condition

Create a new list from a two list using the following condition

Given a two list of numbers, write a program to create a new list such that the new list should contain odd numbers from the first list and even numbers from the second list.

list1 = [10, 20, 25, 30, 35] list2 = [40, 45, 60, 75, 90]

Expected Output:

result list: [25, 35, 40, 60, 90]

• Create an empty list named result_list
• Iterate first list using a for loop
• In each iteration, check if the current number is odd number using num % 2 != 0 formula. If the current number is an odd number, add it to the result list
• Now, Iterate the first list using a loop.
• In each iteration, check if the current number is odd number using num % 2 == 0 formula. If the current number is an even number, add it to the result list
• print the result list

def merge_list(list1, list2): result_list = [] # iterate first list for num in list1: # check if current number is odd if num % 2 != 0: # add odd number to result list result_list.append(num) # iterate second list for num in list2: # check if current number is even if num % 2 == 0: # add even number to result list result_list.append(num) return result_list list1 = [10, 20, 25, 30, 35] list2 = [40, 45, 60, 75, 90] print("result list:", merge_list(list1, list2)) 

Note: Try to solve Python list Exercise

Exercise 11: Write a Program to extract each digit from an integer in the reverse order.

For example, If the given int is 7536, the output shall be “6 3 5 7“, with a space separating the digits.

number = 7536 print("Given number", number) while number > 0: # get the last digit digit = number % 10 # remove the last digit and repeat the loop number = number // 10 print(digit, end=" ") 

Exercise 12: Calculate income tax for the given income by adhering to the below rules

Expected Output:

For example, suppose the taxable income is 45000 the income tax payable is

10000*0% + 10000*10% + 25000*20% = $6000.

income = 45000 tax_payable = 0 print("Given income", income) if income  

1 2 3 4 5 6 7 8 9 10 2 4 6 8 10 12 14 16 18 20 3 6 9 12 15 18 21 24 27 30 4 8 12 16 20 24 28 32 36 40 5 10 15 20 25 30 35 40 45 50 6 12 18 24 30 36 42 48 54 60 7 14 21 28 35 42 49 56 63 70 8 16 24 32 40 48 56 64 72 80 9 18 27 36 45 54 63 72 81 90 10 20 30 40 50 60 70 80 90 100

for i in range(1, 11): for j in range(1, 11): print(i * j, end=" ") print("\t\t") 

for i in range(6, 0, -1): for j in range(0, i - 1): print("*", end=' ') print(" ") 

base = 2 exponent = 5 2 raises to the power of 5: 32 i.e. (2 *2 * 2 *2 *2 = 32)

base = 5 exponent = 4 5 raises to the power of 4 is: 625 i.e. (5 *5 * 5 *5 = 625)

def exponent(base, exp): num = exp result = 1 while num > 0: result = result * base num = num - 1 print(base, "raises to the power of", exp, "is: ", result) exponent(5, 4)