DEV Community: Sakthivel V

Set , Tuples in Python

Sakthivel V — Thu, 04 Jun 2026 16:56:26 +0000

Python Tuples:

Tuples are used to store multiple items in a single variable.
A tuple is a collection which is ordered and unchangeable.
A tuple is like a list, but it cannot be changed (immutable).
Written inside round brackets ().

Ex:

tup = (5, 'Welcome', 7.5, True, [1, 2, 3], {'key': 'value'})
print(tup)

Change Tuple Values:

Once a tuple is created, you cannot change its values. Tuples are unchangeable, or immutable as it also is called.
You can convert the tuple into a list, change the list, and convert the list back into a tuple.

Ex:

x = ("apple", "banana", "cherry")
y = list(x)
y[1] = "kiwi"
x = tuple(y)

print(x)

Join Two Tuples:

To join two or more tuples you can use the + operator

Ex:

tuple1 = ("a", "b" , "c")
tuple2 = (1, 2, 3)

tuple3 = tuple1 + tuple2
print(tuple3)

Set:

Sets are used to store multiple items in a single variable.
A set is a collection which is unordered, unchangeable.

Ex:

thisset = {"apple", "banana", "cherry"}
print(thisset)

Sets cannot have two items with the same value. Duplicate values will be ignored:

Ex:

thisset = {"apple", "banana", "cherry", "apple"}
print(thisset)

Add Items and Remove Item:

To add one item to a set use the add() method.
To add items from another set into the current set, use the update() method.

Ex:

thisset = {"apple", "banana", "cherry"}
thisset.add("orange")
print(thisset)

thisset = {"apple", "banana", "cherry"}
tropical = {"pineapple", "mango", "papaya"}
thisset.update(tropical)
print(thisset)

Remove Item:

To remove an item in a set, use the remove(), or the discard() method.
You can also use the pop() method to remove an item, but this method will remove a random item, so you cannot be sure what item that gets removed.
The return value of the pop() method is the removed item.

Ex:

thisset = {"apple", "banana", "cherry"}
thisset.remove("banana")
print(thisset)


thisset = {"apple", "banana", "cherry"}
x = thisset.pop()
print(x)
print(thisset)

The clear() method empties the set Ex:

thisset = {"apple", "banana", "cherry"}
thisset.clear()
print(thisset)

Join Sets():

There are several ways to join two or more sets in Python.
The union() and update() methods joins all items from both sets.
The intersection() method keeps ONLY the duplicates.
The difference() method keeps the items from the first set that are not in the other set(s).
The symmetric_difference() method keeps all items EXCEPT the duplicates.

Union():

The union() method returns a new set with all items from both sets.
You can use the | operator instead of the union() method, and you will get the same result.

Ex:

set1 = {"a", "b", "c"}
set2 = {1, 2, 3}

set3 = set1 | set2
print(set3)

Intersection():

The intersection() method will return a new set, that only contains the items that are present in both sets.
We can use the & operator instead of the intersection() method, and you will get the same result.

Ex:

set1 = {"apple", "banana", "cherry"}
set2 = {"google", "microsoft", "apple"}

set3 = set1 & set2
print(set3)

Difference():

The difference() method will return a new set that will contain only the items from the first set that are not present in the other set.
You can use the - operator instead of the difference() method, and you will get the same result.

Ex:

set1 = {"apple", "banana", "cherry"}
set2 = {"google", "microsoft", "apple"}

set3 = set1 - set2
print(set3)

Symmetric Differences():

The symmetric_difference() method will keep only the elements that are NOT present in both sets.
You can use the ^ operator instead of the symmetric_difference() method, and you will get the same result.

Ex:

set1 = {"apple", "banana", "cherry"}
set2 = {"google", "microsoft", "apple"}

set3 = set1 ^ set2
print(set3)

List operators in python

Sakthivel V — Tue, 02 Jun 2026 13:49:26 +0000

List operators:

In Python, lists are very flexible. We can add new items, delete items, and reorder items
There are several kinds of list operations,they are:

Add()
Delete()
Reorder()

Add():

append() → Adds an item at the end. Ex:

fruits = ["apple", "banana"]
fruits.append("cherry")
print(fruits)   # ["apple", "banana", "cherry"]

insert() → Adds an item at a specific position. Ex:

fruits.insert(1, "mango")
print(fruits)   # ["apple", "mango", "banana", "cherry"]

extend() → Adds multiple items from another list. Ex:

fruits.extend(["grape", "orange"])
print(fruits)   # ["apple", "mango", "banana", "cherry", "grape", "orange"]

Delete():

pop() → Removes item by index (default: last item). Ex:

fruits.pop()        # removes "orange"
print(fruits)       # ["apple", "mango", "banana", "cherry", "grape"]

remove() → Removes item by value. Ex:

fruits.remove("mango")
print(fruits)       # ["apple", "banana", "cherry", "grape"]

clear() → Removes all items. Ex:

fruits.clear()
print(fruits)       # []

Reorder():

sort() → Sorts items in ascending order. Ex:

numbers = [5, 2, 9, 1]
numbers.sort()
print(numbers)   # [1, 2, 5, 9]

reverse() → Reverses the order of items. Ex:

numbers.reverse()
print(numbers)   # [9, 5, 2, 1]

Bubble Sort Algorithm:

Bubble Sort is one of the easiest sorting methods.
It works by repeatedly comparing two items side by side and swapping them if they are in the wrong order.
After each iteration, the biggest number “bubbles up” to the end of the list.

How Bubble Sort Works:

Start at the beginning of the list.
Compare the first two items.
If the first is bigger, swap them.
Move to the next pair and repeat.
Keep doing this until the end of the list.
After one pass, the largest item is at the end.
Repeat the process for the remaining items until the whole list is sorted.

Python code:

a = [7, 12, 9, 11, 3]

for i in range(len(a)):             
    for j in range(len(a) - 1):      
        if a[j] > a[j + 1]:        
            temp = a[j]             
            a[j] = a[j + 1]
            a[j + 1] = temp

print("Sorted list:", a)

List in python

Sakthivel V — Tue, 02 Jun 2026 13:30:20 +0000

List

Lists are used to store multiple items in a single variable.
Lists are created using square brackets.
List is a built-in data structure used to store an ordered collection of items. They are dynamic, resizable and capable of storing multiple data types.

Ex:

a = [1, 2, 3]
print(a)

b = ["apple", "banana"]
print(b)

List Items - Data Types

List items can be of any data type.
A list with strings, integers and boolean values.

Ex:

list1 = ["apple", 1 , False]
list2 = [1, 5, 7, 9, 3]
list3 = [True, False, False]

print(list1)
print(list2)
print(list3)

List Operations:

There are several kinds of list operations,they are:

Add()
Delete()
Reorder()

Add():

append() → Adds an item at the end.
insert() → Adds an item at a specific position.
extend() → Adds multiple items from another list.

Delete():

pop() → Removes item by index (default: last item).
remove() → Removes item by value.
clear() → Removes all items.

Reorder():

sort() → Sorts items in ascending order.
reverse() → Reverses the order of items.

Practice problems:

Input: [56, 54, 100, 35, 83, 81, 100, 66, 93, 81, 79, 67, 100, 50, 74, 59, 100, 61, 37, 60]
Given math scores, find how many scored centum: 100
Given scores, grade each score: A > 90, B > 80, C > 60, others D
Given scores, count students for each grade

input = [56, 54, 100, 35, 83, 81, 100, 66, 93, 81, 79, 67, 100, 50, 74, 59, 100, 61, 37, 60]
count = 0
for i in input:
    if i == 100:
        count = count + 1
print("Centum scored: ", count)


grade_A = 0
grade_B = 0
grade_C = 0
grade_D = 0

for i in input:
    if i > 90:
        grade_A = grade_A + 1
    elif i > 80:
        grade_B = grade_B + 1
    elif i > 60:
        grade_C = grade_C + 1
    else:
        grade_D = grade_D + 1

print("A_Grade: ", grade_A)
print("B_Grade: ", grade_B)
print("C_Grade: ", grade_C)
print("D_Grade: ", grade_D)

Given numbers, reverse numbers [1, 2, 3] -> [3, 2, 1]

num = [1, 2, 3]
num.reverse()
print("Reversed numbers: ", num)

Given numbers, rotate them in place N times [1, 2, 3, 4, 5] -> [4, 5, 1, 2, 3]

nums = [1, 2, 3, 4, 5]
N = 2

for i in range(N):
    last = nums.pop()
    nums.insert(0, last)   

print("Rotated list:", nums)

Given numbers, double them in place [1, 2, 3, 4, 5] -> [2, 4, 6, 8, 10]

num = [1, 2, 3, 4, 5]
for i in range(len(num)):
    num[i] = num[i] * 2
print("Doubled numbers: ", num)

Sort given numbers

num = [1, 2, 3, 4, 5]
num.sort()
print("Sorted numbers: ", num)

Sum of given numbers

num = [1, 2, 3, 4, 5]
total = 0
for i in num:
    total = total + i
print("Sum of numbers: ", total)

Find even, odd

input = [56, 54, 100, 35, 83, 81, 100]

for i in input:
    if i % 2 == 0:
        print(i, "is even")
    else:
        print(i, "is odd")

Multiply by 2

num = [1, 2, 3, 4, 5]
for i in range(len(num)):
    num[i] = num[i] * 2
print("Multiplied by 2: ", num)

Compare two lists for equality

list1 = [1, 2, 3]
list2 = [4, 5, 6]
if list1 == list2:
    print("Lists are equal")
else:
    print("Lists are not equal")

Python Functions

Sakthivel V — Fri, 29 May 2026 16:21:17 +0000

Functions:

Functions in Python are blocks of code that perform a specific task.
They help us avoid repeating code and make programs easier to read and maintain.

Functions with parameter:

A function that takes input values (parameters).
Ex:

def greet(name):
    print("Hello", name)

greet("Sakthi")

Function Without Parameters:

A function that doesn’t take any input. Ex:

def greet():
    print("Hello, welcome to Python!")

greet()

Function With Return Value:

A function can return a result using the return keyword. Ex:

def add(a, b):
    return a + b

result = add(5, 3)
print("Sum is:", result)

Function With Optional Parameter

We can give parameters a default value. If no value is passed, the default is used. Ex:

def greet(name="Guest"):
    print("Hello", name)

greet("Sakthi")
greet()

Function With Variable Length Parameters

Sometimes we don’t know how many arguments will be passed. We can use (*args)

def numbers(*args):
    total = 0
    for num in args:
        total += num 
    print("Sum is:", total)

numbers(1, 2, 3, 4, 5)

Practice problems:

data = "John,30,40,50,60\nDave,10,20,30,45,50\nAdam,40,95,87,67,50"
total, pass / fail, average, rank

data = "John,30,40,50,60,70\nDave,10,20,30,45,50\nAdam,40,95,87,67,50"

students = data.split("\n")

for std in students:

    record = std.split(",")

    name = record[0]
    total = 0
    result = "Pass"

    for i in range(1, len(record)):

        mark = int(record[i])
        total += mark

        if mark < 36:
            result = "Fail"

    avg = total / 5

    record.append(total)
    record.append(avg)
    record.append(result)

    print(record)

Calculator with variable length arguments, and return values

def add(*args):
    total = 0

    for i in args:
        total = total + i

    return total


def sub(*args):
    total = args[0]

    for i in range(1, len(args)):
        total = total - args[i]

    return total


def mul(*args):
    total = 1

    for i in range(1, len(args)):
        total = total * args[i]

    return total


def div(*args):
    total = args[0]

    for i in range(1, len(args)):
        total = total / args[i]

    return total


def floor_div(*args):
    total = args[0]

    for i in range(1, len(args)):
        total = total // args[i]

    return total


def mod(*args):
    total = args[0]

    for i in range(1, len(args)):
        total = total % args[i]

    return total


def power(*args):
    total = args[0]

    for i in range(1, len(args)):
        total = total ** args[i]

    return total


print("Addition:", add(1, 2, 3, 4))
print("Subtraction:", sub(10, 2, 3))
print("Multiplication:", mul(2, 3, 4))
print("Division:", div(100, 2, 5))
print("Floor Division:", floor_div(100, 3, 2))
print("Modulus:", mod(10, 3))
print("Power:", power(2, 3, 2))

For loop in Python

Sakthivel V — Wed, 27 May 2026 14:35:55 +0000

For loop:

A for loop is used to repeat a block of code for a fixed number of times
To loop through a set of code , we can use the range() function.
The range() function increment the sequence by 1, however it is possible to increment the value by adding a third parameter: range(2, 30, 3):

Syntax:

for (variable) in (sequence):
code block

Examples :

# Print 1, 2, 3 … 10
# Print 2, 4 ,6 … 20
# Print Table given a number a. Ex: 2 -> 1x2, 2x2, 3x2 … 10x2
# Find all odd numbers until given number a. Ex: 10 -> 1, 3, 5, 7, 9
# Find all numbers divisible by 3 until given number a. Ex: 10 -> 3, 6, 9
# Find all numbers divisible by 3 and 5 until given number a. Ex: 50 -> 15, 30, 45
# Sum of natural numbers until given number a. Ex: input: 4 -> 1 + 2 + 3 + 4 -> 10
# Find factorial of given number a. Ex: input 5 -> 5 * 4 * 3 * 2 * 1 -> 120

Answers:

1).

def print_1_10():
for i in range(1,11):
print(i)
print_1_10()

2).

def print_2_20():
for i in range(2,22,2):
print(i)
print_2_20()

3).

def print_table():
for i in range(1,11):
print(i*2)
print_table()

4).

def print_odd(n):
for i in range(1,n+1):
if(i%2!=0):
print (i)
n=int(input("Enter a number: "))
print_odd(n)

5).

n=int(input("Enter a number: "))
def print_div_by_3(n):
for i in range(1,n+1):
if(i%3==0):
print (i)
print_div_by_3(n)

6).

def print_div_by_3_and_5(n):
for i in range(1,n+1):
if(i%3==0 and i%5==0):
print (i)
n=int(input("Enter a number: "))
print_div_by_3_and_5(n)

7).

n=int(input("Enter a number: "))
def print_sum(n):
sum=0
for i in range(1,n+1):
sum = sum + i
print(sum)
print_sum(n)

8).

def print_fact(n):
fact=1
for i in range(1,n+1):
fact = fact * i
print(fact)
n=int(input("Enter a number: "))
print_fact(n)

*References: *

https://www.w3schools.com/Python/python_for_loops.asp
https://www.geeksforgeeks.org/python/python-for-loops/

Cracking the Coding Interview

Sakthivel V — Sun, 24 May 2026 16:53:01 +0000

Technical Interview Process

A) Importance of Algorithms & Coding

Algorithms are a major part of technical interviews.
Interviewers mainly focus on problem-solving skills.
Most interviews are around 45 minutes long.
Sometimes only one coding problem is discussed in the entire interview.
Interviewers observe how candidates think and approach the solution.

B) Skills Checked by Interviewers

1. Analytical Skills
Interviewers check:

Problem-solving ability
Logical thinking
Solution optimization
Decision-making skills

2. Coding Skills
Interviewers observe:

Clean code writing
Proper formatting
Readable code
Error handling
Code organization

3. Technical Knowledge
Important topics include:

Data Structures
Algorithms
Trees
Graphs
Sorting
Computer Science fundamentals

4. Experience
Companies also check:

Projects completed
Technical decisions taken
Initiative and interest
Real-world problem solving

5. Communication & Culture Fit
Communication is very important because employees work in teams.

Interviewers observe:

Confidence
Communication style
Teamwork
Personality fit with company culture

Loops in Python

Sakthivel V — Fri, 22 May 2026 10:57:35 +0000

Loops are used to execute a block of code repeatedly.
The main types are,

For loops
While loops.

Syntax:

While loop:

while (condition):
# code block

For loop:

for (variable) in (sequence):
# code block

While loop:

While loop repeatedly executes a block of code as long as the given condition remains true. When the condition becomes false, it will terminate the loop and print the remaining.

Example: While Loop
1).

i= 1
while i<= 5:
print("Number:", i)
i+= 1
This code is used to print the numbers from 1 to 5.

2).
i= 1
while i<= 10:
print("Number:", i*2)
i+= 1
This code is used to print multiples of 2.

3).
i= 1
fact = 1
while i<=5:
fact = fact * i
i= i + 1
print("Factorial of 5 is:", fact)
This code is used to print factorial of a number.

For loop:

A for loop is used to repeat a block of code for a fixed number of times

for (variable) in (sequence):
# code block

Example: For Loop

n = [1,2,3,4,5]
for x in n:
print(x)

Data Structure problem:

Binary search:

Operators in Python

Sakthivel V — Thu, 14 May 2026 14:12:56 +0000

Operators are used to perform operations on values and variables.
Types of Operators in Python:

Arithmetic operators
Logical operators
Comparision operators

Arithmetic operators:

Arithmetic operators are used to perform operations like addition, subtraction, multiplication and division.

Ex:
a = 10
b = 5
print("Addition:", a + b)

print("Subtraction:", a - b)
print("Multiplication:", a * b)

print("Division:", a / b)
print("Floor Division:", a // b)

print("Modulus:", a % b)
print("Power:", a ** b)

Comparison operators:

Comparision operator is used to compare the values.
It returns boolean values

Ex:
a = 10
b = 20
print(a > b)
print(a < b)
print(a == b)
print(a != b)
print(a >= b)
print(a <= b)

Logical operators:

Logical operators performs AND, OR operations.
It is used to combined statements

Ex:
a=10
b=5
print(a>5 and a>7)
print(b<6 or a<9)