Python/recursions/recursive_digit_sum.py
2024-10-18 23:13:55 +05:30

58 lines
1.8 KiB
Python

"""
The super digit problem is defined as follows:
Given an integer n represented as a string and an integer k,
the goal is to find the super digit of the number formed by concatenating
the integer n k times.
The super digit of a number is defined recursively:
- If the number has only one digit, that digit is the super digit.
- Otherwise, the super digit is the super digit of the sum of its digits.
For example, for n = "9875" and k = 4, the concatenated number is:
super_digit(9875987598759875), which can be reduced by summing its digits.
"""
from __future__ import annotations
def super_digit(n_str: str, repetitions: int) -> int:
"""
Computes the super digit of a number formed by concatenating n_str repetitions times.
Parameters:
n_str (str): The string representation of the integer.
repetitions (int): The number of times to concatenate n_str.
Returns:
int: The super digit of the concatenated number.
>>> super_digit("148", 3)
3
>>> super_digit("9875", 4)
8
>>> super_digit("123", 3)
9
"""
# Calculate the initial sum of the digits in n_str
digit_sum = sum(int(digit) for digit in n_str)
# Multiply the sum by repetitions
total_sum = digit_sum * repetitions
# Recursive function to find the super digit
while total_sum >= 10:
total_sum = sum(int(digit) for digit in str(total_sum))
return total_sum
if __name__ == '__main__':
# Read input and split it into n_str and repetitions
first_multiple_input = input().rstrip().split()
n_str = first_multiple_input[0] # n as a string
repetitions = int(first_multiple_input[1]) # repetitions as an integer
# Call the super_digit function and print the result
result = super_digit(n_str, repetitions)
print(result)