Python Coding challenge - Day 518| What is the output of the following Python Code?

Code Explanation:

1. Function Definition

def dec_to_bin(n):

This defines a function dec_to_bin that takes an integer n.

The function’s goal is to convert a decimal number (n) to its binary representation using recursion.

2. Base Case: When n is 0

    if n == 0:

        return ""

This is the base case for the recursive function.

When n becomes 0, return an empty string.

This stops the recursion and begins building the final binary string.

3. Recursive Case: Divide and Conquer

    return dec_to_bin(n // 2) + str(n % 2)

This line performs the core recursive logic:

n // 2: Divides the number by 2 (integer division), moving toward the base case.

Recursive call: Converts the quotient into binary.

n % 2: Gets the remainder, which is either 0 or 1—this is the current binary digit.

Combines: Appends the current binary digit to the end of the binary string returned from the recursive call.

4. Function Call and Output

print(dec_to_bin(10))

Let’s walk through what happens step-by-step for dec_to_bin(10):

Step-by-step breakdown:

dec_to_bin(10) 

= dec_to_bin(5) + "0"

= (dec_to_bin(2) + "1") + "0"

= ((dec_to_bin(1) + "0") + "1") + "0"

= (((dec_to_bin(0) + "1") + "0") + "1") + "0"

= ((("" + "1") + "0") + "1") + "0"

= ("1" + "0") + "1" + "0"

= "10" + "1" + "0"

= "1010"

Final Output

1010

The binary representation of decimal 10 is 1010.