Lowercase letter diamond

Write a Python program to print the letters a to y in rows of 1, 3, 5, 7, 5, 3, 1 letters.

a
b c d
e f g h i
j k l m n o p
q r s t u
v w x
y

Approach

1. Same idea as the previous program with different row sizes.

Solution

import string letters = iter(string.ascii_lowercase)for size in [1, 3, 5, 7, 5, 3, 1]:    print(" ".join(next(letters) for _ in range(size)))

a
b c d
e f g h i
j k l m n o p
q r s t u
v w x
y

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Uppercase letter diamond

Write a Python program to print the letters A to Y in rows of 1, 2, 3, 4, 5, 4, 3, 2, 1 letters.

A
B C
D E F
G H I J
K L M N O
P Q R S
T U V
W X
Y

Approach

1. Keep a letter counter and print the right number of letters on each row.

Solution

sizes = [1, 2, 3, 4, 5, 4, 3, 2, 1]code = ord("A")for size in sizes:    row = [chr(code + i) for i in range(size)]    print(" ".join(row))    code += size

A
B C
D E F
G H I J
K L M N O
P Q R S
T U V
W X
Y

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Maximum number in a list

Write a Python program to find the largest number in a list using a loop.

[12, 14, 45, 88, 63, 97, 88]

Maximum number: 97

Approach

1. Assume the first item is the largest and replace it whenever a bigger one appears.

Solution

numbers = [12, 14, 45, 88, 63, 97, 88]largest = numbers[0]for n in numbers[1:]:    if n > largest:        largest = nprint("Maximum number:", largest)

Maximum number: 97

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Copy and sort descending

Write a Python program to copy elements from one list into an empty list and print them in descending order.

[2, 5, 8, 0, 1, 4]

[8, 5, 4, 2, 1, 0]

Approach

1. Copy with a loop, then sort with reverse=True.

Solution

a = [2, 5, 8, 0, 1, 4]b = []for x in a:    b.append(x)b.sort(reverse=True)print(b)

[8, 5, 4, 2, 1, 0]

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Sort a list with loops

Write a Python program to sort a list using loops (without sort()).

[6, 8, 2, 3, 1, 0, 5]

[0, 1, 2, 3, 5, 6, 8]

Approach

1. Bubble sort: compare neighbours and swap them when they are in the wrong order; repeat.

Solution

numbers = [6, 8, 2, 3, 1, 0, 5]n = len(numbers)for i in range(n - 1):    for j in range(n - 1 - i):        if numbers[j] > numbers[j + 1]:            numbers[j], numbers[j + 1] = numbers[j + 1], numbers[j]print(numbers)

[0, 1, 2, 3, 5, 6, 8]

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Count special characters in a file

Write a Python program to count the special characters in a file.

file.txt: "student@gmail.com" / "##comment"

4

Approach

1. Count characters that are not letters, digits or whitespace.

Solution

with open("file.txt", "w") as f:    f.write("student@gmail.com\n##comment\n") count = 0with open("file.txt") as f:    for line in f:        for ch in line:            if not ch.isalnum() and not ch.isspace():                count += 1print(count)

4

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Count uppercase letters in a file

Write a Python program to count the uppercase letters in a file.

file.txt: "Virat Kohli scored 100 in the last match"

2

Approach

1. Count characters where isupper() is True.

Solution

with open("file.txt", "w") as f:    f.write("Virat Kohli scored 100 in the last match") with open("file.txt") as f:    text = f.read()print(sum(1 for ch in text if ch.isupper()))

2

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Count digits in a file

Write a Python program to count the digits in a file.

file.txt: "Virat Kohli scored 100 in the last match"

3

Approach

1. Loop over every character of the file and count isdigit().

Solution

with open("file.txt", "w") as f:    f.write("Virat Kohli scored 100 in the last match") count = 0with open("file.txt") as f:    for ch in f.read():        if ch.isdigit():            count += 1print(count)

3

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Count characters in a file

Write a Python program to count the characters in a file (letters, digits, punctuation and spaces, not counting newlines).

file.txt: "I'm learning python" / "At" / "Sqatools"

29

Approach

1. Read the file line by line and add the length of each line without its newline.

Solution

with open("file.txt", "w") as f:    f.write("I'm learning python\nAt\nSqatools\n") count = 0with open("file.txt") as f:    for line in f:        count += len(line.rstrip("\n"))print(count)

29

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Stop at 6 with a for loop

Write a Python program to print 1 to 10 but stop when the number is 6, using a for loop.

1
2
3
4
5

Approach

1. break leaves the for loop.

Solution

for n in range(1, 11):    if n == 6:        break    print(n)

1
2
3
4
5

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