Python Coding challenge - Day 120 | What is the output of the following Python Code?

 

Code :

def sum(num):

    if num == 1:

        return 1

    return num + sum(num - 1)

print(sum(5))

Solution and Explanation:

Here's how the function works:

The function sum takes a parameter num.
The base case is defined with if num == 1:. If num is 1, the function returns 1.
If the base case is not met, the function returns num + sum(num - 1). This is the recursive step, where the sum of the current num and the sum of the numbers from 1 to num - 1 is calculated.
The print(sum(5)) statement calls the sum function with the argument 5 and prints the result.
Let's trace the function call for sum(5):

sum(5) returns 5 + sum(4)
sum(4) returns 4 + sum(3)
sum(3) returns 3 + sum(2)
sum(2) returns 2 + sum(1)
sum(1) returns 1 (base case)
Now we substitute these values back:

sum(2) returns 2 + 1 = 3
sum(3) returns 3 + 3 = 6
sum(4) returns 4 + 6 = 10
sum(5) returns 5 + 10 = 15
So, the final result printed by print(sum(5)) is 15.