How to write and use class variable in Python

class Circle:
    pi = 3.141592653589793238
    def __init__(self, radius):
        self.r = radius
    def calc_circum(self):
        return 2*self.r*Circle.pi
    def calc_area(self):
        return Circle.pi*self.r*self.r

C1 = Circle(5)
print(C1.calc_area())
print(C1.calc_circum())

Class Object Program using multiple methods in Python

class Laptop():
    def __init__(self, brand_name, model_name, price):
        #initializing instance varaibles
        self.bn = brand_name
        self.mn = model_name
        self.p = price

    def apply_disc(self, disc):
        after_disc = self.p - (self.p * (disc/100))
        return after_disc

L1 = Laptop('Lenovo', 'ABCD', 40000)
L2 = Laptop('Dell', 'EFGH', 50000 )
L3 = Laptop('HP', 'IJKL', 60000)

print(L1.apply_disc(20))

# print(L1.bn, L1.mn, L1.p)
# print(L2.bn, L2.mn, L2.p)
# print(L3.bn, L3.mn, L3.p)

Basic Class and Object implementation using Python

The init() method gets called depends upon how many objects we create of that class.
init() method always starts with self keyword according to naming convention. It is not always necessary to write self.
init() is a method as well as a constructor in Python.

class Person:
    def __init__(self, first_name, last_name, age):
        print("Init method / constructor gets called here.")
        self.fn = first_name
        self.ln = last_name
        self.a = age

p1 = Person('Sayan', 'Dey', 21)
p2 = Person('Dey', 'Sayan', 21)
print(p1.fn)
print(p2.ln)

Sort Colors in Python without using sort() – Google Interview Question

def sort_colour(arr):
    red = 0
    blue = 0
    for i in range(len(arr)):
        if arr[i] == 1:
            red+=1
        elif arr[i] == 2:
            blue+=1
    return [1]*red + [2]*blue + [3]*(len(arr) - red - blue)

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

Sieve of Eratosthenes in Python

from math import sqrt
def sieve_prime(num):
    prime_arr = [1] * (num+1) 
    prime_arr[0] = 0 
    prime_arr[1] = 0 
    for i in range(2, int(sqrt(num))+1):
        if prime_arr[i] == 1:
            j=2
            while i*j<num+1:
                prime_arr[j*i] = 0
                j+=1
    return prime_arr

print(sieve_prime(15))

Find Prime Number using shortest time complexity using Python

from math import sqrt
def check_Prime(num):
    if num>1:
        for i in range(2, int(sqrt(num/2))):
            if(num%i==0):
                return(f"{num} is Not Prime")
            return(f"{num} is Prime")
    
print(check_Prime(18))

Sum of Maximum Sub Array elements in Python

def max_sum_SubArray(arr):
    current_sum = 0
    max_so_far = arr[0]
    for i in range(len(arr)):
        current_sum = current_sum + arr[i]
        if max_so_far < current_sum:
            max_so_far = current_sum
        elif current_sum < 0:
            current_sum = 0
    return max_so_far

arr = [4, -3, -2, 2, 3, 1, -2, -3, 6, -6, -4, 2, 1]
print(max_sum_SubArray(arr))

Length of last word from a given string using Python

def length():
    string = input("Enter the stirng : ").split()
    last_word = len(string[-1])
    print(last_word)

length()

Remove duplicated from Sorted Array in Python

def remove_duplicates(arr):
    arr = sorted(arr)
    # print(arr)
    rmv_dpl = list(set(arr))
    return rmv_dpl

a = [9, 7, 5, 8, 6, 1, 2, 4, 3, 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
print(remove_duplicates(a))

Hotel Booking System using Python

def hotel_booking(arr, dept, room):
    event = [(t, 'RED') for t in arr] + [(t, "BLUE") for t in dept]
    event = sorted(event)
    
    guest = 0
    for e in event:
        if e[1] == 'RED':
            guest+=1
        else:
            guest-=1
        
        if guest > room:
            return 'Sorry the rooms are full'
    return 'Rooms available'

arr = [1, 3, 5]
dept = [2, 6, 8]
k = 1

print(hotel_booking(arr, dept, k))