Python - Day 9 - Recursion - 30 Days of Code

Concepts:
- Algorithmic Concept, Recursion; Expressing the solution / implementation of a function as a solution of a smaller subproblem / related function call
- Implementing factorial with recursion
- Introduction to the Call Stack; Data structure under the hood used to assign memory used in a function call (memory used for variables, parameters used in a function call)
- Control flow of a recursive function call; A recursive function call can't be completed and popped off the call stack till its child recursive call returns the result it needs.
- Iterative Implementation of Recursion; A constant memory-complexity implementation.

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