Python Data Structures and Algorithms - Recursion: Sum of a non-negative integer

Last update on April 19 2025 12:55:42 (UTC/GMT +8 hours)

6. Sum of Digits of an Integer Using Recursion

Write a Python program to get the sum of a non-negative integer using recursion.

Sample Solution:

Python Code:

# Define a function named sumDigits that calculates the sum of the digits of a given number 'n'
def sumDigits(n):
    # Check if 'n' is 0 (base case for summing digits)
    if n == 0:
        # If 'n' is 0, return 0 (no digits to sum)
        return 0
    else:
        # If 'n' is not 0, calculate the sum of the last digit (n % 10) and
        # recursively call the sumDigits function on the remaining digits (n / 10)
        return n % 10 + sumDigits(int(n / 10))

# Print the result of calling the sumDigits function with the input value 345
print(sumDigits(345))

# Print the result of calling the sumDigits function with the input value 45
print(sumDigits(45))

Sample Output:

12                                                                                                            
9

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to recursively compute the sum of the digits of a non-negative integer.
Write a Python program to implement a function that returns the digit sum of an integer using recursion without converting to a string.
Write a Python program to recursively calculate the sum of digits and count the number of recursive calls made.
Write a Python program to recursively sum the digits of an integer and determine if the resulting sum is even or odd.

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Previous: Write a Python program to solve the Fibonacci sequence using recursion.
Next: Write a Python program to calculate the sum of the positive integers of n+(n-2)+(n-4)... (until n-x =< 0).

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