What is recursion?

Recursion is the process of a function calling itself. In programming, a recursive function is a function that calls itself directly or indirectly. To avoid an infinite loop, a recursive function must have a base case, which stops it from calling itself.

Examples of use:

• Traversing data structures (e.g., trees).
• Solving problems that can be broken down into smaller subproblems of the same type (e.g., calculating factorial).

Example of calculating factorial using recursion:

def factorial(n):
  # Base case: factorial of 0 is 1
  if n == 0:
    return 1
  # Recursive case: factorial n = n * factorial(n-1)
  else:
    return n * factorial(n - 1)

# Example of use
result = factorial(5)
# result will be 120

Disadvantages of recursion:

• It can consume a lot of memory due to the call stack.
• It can be less efficient compared to iterative solutions for some problems.
• It can lead to stack overflow with deep recursive calls.