que.md

a = "developer"
b = "devel0perX"

max_len = max(len(a), len(b))

for i in range(max_len):
    ch1 = a[i] if i < len(a) else "-"
    ch2 = b[i] if i < len(b) else "-"
    
    if ch1 != ch2:
        print(f"Pos {i}: {ch1} != {ch2}")

ip = "192.168.0.1"

parts = ip.split(".")
valid = True

if len(parts) != 4:
    valid = False
else:
    for p in parts:
        if not p.isdigit():
            valid = False
            break
        if not 0 <= int(p) <= 255:
            valid = False
            break
        if p != str(int(p)):  # no leading zeros
            valid = False
            break

print(valid)

def final_position(commands):
    x = y = 0
    cmds = commands.split(";")

    for cmd in cmds:
        if not cmd.strip():
            continue

        direction, steps = cmd.strip().split()
        steps = int(steps)

        if direction == "UP":
            y += steps
        elif direction == "DOWN":
            y -= steps
        elif direction == "LEFT":
            x -= steps
        elif direction == "RIGHT":
            x += steps

    return (x, y)


print(final_position("UP 5; LEFT 3; DOWN 2; RIGHT 4"))

sentence = "apple is an awesome idea but orange exists"
vowels = "aeiouAEIOU"

count = 0
for w in sentence.split():
    if w[0] in vowels:
        count += 1

print(count)

#️⃣ 1. LIST – Important 10 Problems

1️⃣ Remove duplicates (keep order)

arr = [2, 5, 2, 8, 5, 9]
seen = []
for x in arr:
    if x not in seen:
        seen.append(x)
print(seen)

2️⃣ Find second largest element

arr = [10, 50, 20, 40]
arr2 = arr.copy()
arr2.remove(max(arr2))
print(max(arr2))

3️⃣ Move all zeros to end

arr = [0, 3, 0, 2, 0, 9]
res = []
zero = 0

for x in arr:
    if x == 0:
        zero += 1
    else:
        res.append(x)

res += [0] * zero
print(res)

4️⃣ Merge two lists alternatively

a = [1, 3, 5]
b = [2, 4, 6, 7]

i = 0
res = []

while i < len(a) or i < len(b):
    if i < len(a): res.append(a[i])
    if i < len(b): res.append(b[i])
    i += 1

print(res)

5️⃣ Count frequency of each number

arr = [1, 2, 2, 3, 3, 3]
freq = {}

for x in arr:
    freq[x] = freq.get(x, 0) + 1

print(freq)

6️⃣ Reverse list without using reverse()

arr = [1,2,3,4,5]
rev = []

for i in range(len(arr)-1, -1, -1):
    rev.append(arr[i])

print(rev)

7️⃣ Sum of even & odd numbers in list

arr = [1, 2, 3, 4, 5, 6]
even = odd = 0

for x in arr:
    if x % 2 == 0:
        even += x
    else:
        odd += x

print(even, odd)

8️⃣ Remove adjacent duplicates

arr = [1,1,2,2,3,1,1]
res = [arr[0]]

for i in range(1, len(arr)):
    if arr[i] != arr[i-1]:
        res.append(arr[i])

print(res)

9️⃣ Find common elements in two lists

a = [1,2,3,4]
b = [3,4,5,6]
common = []

for x in a:
    if x in b:
        common.append(x)

print(common)

🔟 Find elements greater than average

arr = [10, 20, 30, 40]
avg = sum(arr) / len(arr)

res = []
for x in arr:
    if x > avg:
        res.append(x)

print(res)

tuple

t = (10, 20, 30, 40)
for i in range(len(t)):
    if t[i] == 30:
        print(i)

2️⃣ Find index of element

t = (11,5,99,3)
mx = t[0]
mn = t[0]

for x in t:
    if x > mx: mx = x
    if x < mn: mn = x

print(mx, mn)

dict

1️⃣ Count Frequency of Each Word in a Sentence
Input
Sky is blue and the sky is clear

Expected Output
{'sky': 2, 'is': 2, 'blue': 1, 'and': 1, 'the': 1, 'clear': 1}

sentence = "Sky is blue and the sky is clear"
sentence = sentence.lower().split()

freq = {}

for word in sentence:
    if word in freq:
        freq[word] += 1
    else:
        freq[word] = 1

print(freq)

3️⃣ Reverse Keys and Values
Input
{'a': 1, 'b': 2, 'c': 3}

Output
{1: 'a', 2: 'b', 3: 'c'}

✅ Code
d = {'a': 1, 'b': 2, 'c': 3}

rev = {}
for k, v in d.items():
    rev[v] = k

print(rev)

6️⃣ Character Frequency Without Using Counter

Input
"success"

Output
{'s': 3, 'u': 1, 'c': 2, 'e': 1}

✅ Code
s = "success"
freq = {}

for ch in s:
    if ch in freq:
        freq[ch] += 1
    else:
        freq[ch] = 1

print(freq)

palidrome

a="12trt1"

b=a[::-1]

if a==b:
    print("is aplidrome")
else:
    print("no")

6️⃣ Check if two strings are anagrams

a = "listen"
b = "silent"

if sorted(a.lower()) == sorted(b.lower()):
    print(True)
else:
    print(False)

4️⃣ Count uppercase, lowercase, digits, and spaces

s = "Cts 2026 GenC"
upper = lower = digit = space = 0

for ch in s:
    if ch.isupper():
        upper += 1
    elif ch.islower():
        lower += 1
    elif ch.isdigit():
        digit += 1
    elif ch == " ":
        space += 1

print(upper, lower, digit, space)

2️⃣ Count vowels and consonants

s = "cognizant"
vowels = "aeiouAEIOU"
v_count = c_count = 0

for ch in s:
    if ch in vowels:
        v_count += 1
    else:
        c_count += 1

print("Vowels:", v_count, "Consonants:", c_count)

Loops

1️⃣ Print numbers from 1 to 10

for i in range(1, 11):
    print(i, end=" ")

2️⃣ Print even numbers between 1 to 50

for i in range(1, 51):
    if i % 2 == 0:
        print(i, end=" ")

3️⃣ Sum of first N natural numbers

N = 10
total = 0

for i in range(1, N+1):
    total += i

print(total)

5️⃣ Fibonacci series up to N terms

N = 7
a, b = 0, 1

for i in range(N):
    print(a, end=" ")
    a, b = b, a+b

function

def factorial(n):
    if n == 0 or n == 1:
        return 1
    return n * factorial(n-1)

print(factorial(5))
print(factorial(7))

def validate_password(pwd):
    if len(pwd) > 8:
        print("Valid")
    else:
        print("Invalid")

validate_password("CTS2026")
validate_password("StrongPassword")

Oops

class BankAccount:
    def __init__(self, name, balance):
        self.name = name
        self.balance = balance

    def deposit(self, amount):
        self.balance += amount

    def withdraw(self, amount):
        if amount <= self.balance:
            self.balance -= amount
        else:
            print("Insufficient balance")

    def show_balance(self):
        print(self.name, "balance:", self.balance)


# Usage
account = BankAccount("Alice", 1000)
account.deposit(500)
account.withdraw(300)
account.show_balance()

class Student:
    def __init__(self, name, roll_no, marks):
        self.name = name
        self.roll_no = roll_no
        self.marks = marks  # List of marks

    def average_marks(self):
        return sum(self.marks) / len(self.marks)

    def display(self):
        print(self.name, "Roll No:", self.roll_no)
        print("Average marks:", self.average_marks())


# Usage
student = Student("Bob", 101, [80, 90, 85])
student.display()

class Cat:
    def mood(self): 
       print("Grumpy") 
    def sound(self): 
       print("Meow") 
 
class Dog:
    def mood(self): 
       print("Happy") 
    def sound(self): 
       print("Woof") 
 
hello_kitty = Cat()
hello_puppy = Dog()
 
for pet in (hello_kitty, hello_puppy):
    pet.mood()
    pet.sound()

5. First non-repeating character

def first_non_rep(s):
    for ch in s:
        if s.count(ch) == 1:
            return ch
    return None

print(first_non_rep("swiss"))

Remove duplicates (preserve order)

def rem_dup(s):
    res = ""
    for ch in s:
        if ch not in res:
            res += ch
    return res

print(rem_dup("programming"))

Rotate string by K

def rotate_string(s, k):
    k %= len(s)
    return s[-k:] + s[:-k]

print(rotate_string("abcdef", 2))  # efabcd

5. Password validation

def validate_password(p):
    if len(p) < 8:
        return False

    low = up = dig = sp = 0
    
    for ch in p:
        if ch.islower(): low = 1
        elif ch.isupper(): up = 1
        elif ch.isdigit(): dig = 1
        else: sp = 1

    return low and up and dig and sp

print(validate_password("Aa1@abcd"))

Count “special substrings” (first & last char same)

def special_substrings(s):
    count = 0
    for i in range(len(s)):
        for j in range(i+1, len(s)):
            if s[i] == s[j]:
                count += 1
    return count

print(special_substrings("abcaac"))  # Output: 4

gcd

def gcd(a, b):
    # If b becomes 0, a is the GCD
    if b == 0:
        return a
    # Recursively call gcd with (b, a % b)
    return gcd(b, a % b)

# Example
x = 36
y = 60

print("GCD is:", gcd(x, y))

leap year

year = 2000

if (year % 400 == 0) or (year % 4 == 0 and year % 100 != 0):
    print("yes")
else:
    print("no")

1️⃣ Handle division by zero

Question:

Write a program to divide two numbers and handle ZeroDivisionError.

try: a = int(input("Enter number: ")) b = int(input("Enter divisor: ")) print(a / b) except ZeroDivisionError: print("Cannot divide by zero!")

2️⃣ Handle invalid integer input

Question:

Take a number from the user and handle ValueError if input is not an integer.

try: num = int(input("Enter an integer: ")) print("You entered:", num) except ValueError: print("Invalid input! Please enter an integer.")

3️⃣ File not found exception

Question:

Read a file and handle FileNotFoundError.

try: f = open("data.txt") print(f.read()) except FileNotFoundError: print("File does not exist!")

4️⃣ Multiple exceptions in one block

Question:

Divide numbers and also check if input is valid.

try: a = int(input()) b = int(input()) print(a / b) except (ValueError, ZeroDivisionError): print("Invalid input or division by zero!")

5️⃣ Use finally block

Question:

Write a program that prints “Done” no matter what happens.

try: x = int(input()) print("Square:", x * x) except ValueError: print("Please enter a valid number.") finally: print("Done!")

6️⃣ Custom exception for negative age

Question:

Raise a custom exception if age < 0.

class NegativeAgeError(Exception): pass

age = int(input("Enter age: "))

try: if age < 0: raise NegativeAgeError("Age cannot be negative!") print("Age =", age) except NegativeAgeError as e: print(e)

7️⃣ Using else in exception handling

Question:

Print a message if no error happens.

try: n = int(input("Enter number: ")) except ValueError: print("Invalid number!") else: print("Valid input:", n)

8️⃣ Nested try–except

Question:

Handle errors inside nested blocks.

try: a = int(input()) try: print(10 / a) except ZeroDivisionError: print("Inner: cannot divide by zero") except ValueError: print("Outer: invalid input")

9️⃣ Raise an exception manually

Raise TypeError if input is not string.

data = 10

try: if not isinstance(data, str): raise TypeError("Only strings allowed") print(data) except TypeError as e: print(e)

🔟 Handle KeyError

Question:

Dictionary lookup with exception handling.

d = {"name": "John", "age": 25}

try:
    print(d["salary"])
except KeyError:
    print("Key not found!")

password = input("Enter password: ")

has_upper = False
has_lower = False
has_digit = False

# Check each character
for ch in password:
    if ch.isupper():
        has_upper = True
    elif ch.islower():
        has_lower = True
    elif ch.isdigit():
        has_digit = True

# Final validation
if len(password) >= 8 and has_upper and has_lower and has_digit:
    print("Valid Password")
else:
    print("Invalid Password")