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Poridhi: Basic Programming & Math


Basic Programming and math related problems:

Extracting digits means breaking a number like 1234 into [1, 2, 3, 4], often using string conversion or modulo/division. Counting digits involves finding how many digits are in a number using length of a string or repeated division. Reversing an integer flips its digits (e.g., 123 becomes 321), with care for signs and 32-bit limits. A palindrome number reads the same forward and backward, often checked by comparing the original and reversed number. Armstrong numbers are those equal to the sum of their digits each raised to the number of digits, like 153 = 1³ + 5³ + 3³.

To find the sum of all divisors of a number, loop through integers and check which divide the number without a remainder. Prime numbers are only divisible by 1 and themselves, and checking up to the square root is efficient. GCD, the greatest common divisor of two numbers, can be found using a simple loop or more efficiently with the Euclidean algorithm, which uses repeated modulo operations.

✅ Extract Digits from a Given Number

def extract_digits(n):
return [int(d) for d in str(abs(n))] print(extract_digits(12345)) # Output: [1, 2, 3, 4, 5]

✅ Count Digits from a Given Number

def count_digits(n):
    return len(str(abs(n)))

print(count_digits(12345))  # Output: 5

✅ LeetCode Reverse Integer

def reverse(x):

    INT_MAX = 2**31 - 1
    INT_MIN = -2**31

    sign = -1 if x < 0 else 1
    x = abs(x)
    rev = int(str(x)[::-1])

    rev *= sign
    if rev < INT_MIN or rev > INT_MAX:
        return 0
    return rev

print(reverse(123))    # Output: 321
print(reverse(-120))   # Output: -21

✅ LeetCode Palindrome Number

def is_palindrome(x):

    if x < 0:
        return False
    return str(x) == str(x)[::-1]

print(is_palindrome(121))  # Output: True
print(is_palindrome(-121)) # Output: False

✅ Armstrong Number

(A number equal to the sum of its digits each raised to the power of number of digits)

def is_armstrong(n):
    digits = [int(d) for d in str(n)]
    power = len(digits)
    return n == sum(d ** power for d in digits)

print(is_armstrong(153))  # Output: True (1³ + 5³ + 3³ = 153)

✅ Sum of All the Divisors of a Given Number

import math
def sum_of_divisors(n):
    return sum((i + (n//i)) for i in range(1, int(math.sqrt(n)) + 1) if n % i == 0)

print(sum_of_divisors(12))  # Output: 28 (1+2+3+4+6+12)

✅ Prime Number Check

def is_prime(n):
    if n <= 1:
        return False
    for i in range(2, int(n**0.5) + 1):
        if n % i == 0:
            return False
    return True

# Example
print(is_prime(29))  # Output: True
✅ GCD (Greatest Common Divisor: Brute Force)

def gcd_linear(a, b):
    gcd = 1
    for i in range(1, min(a, b) + 1):
        if a % i == 0 and b % i == 0:
            gcd = i
    return gcd

print(gcd_linear(48, 18))  # Output: 6

✅ GCD (Greatest Common Divisor: Euclidean Algorithm)


def gcd(a, b):
    while b:
        a, b = b, a % b
    return a

print(gcd(48, 18))  # Output: 6

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