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Recursion for Coding Interviews in Python

# Problem Statement
Imagine you have been given the task to schedule some tasks. The tasks are represented as **vertices** of the graph, and if a task $u$ must be completed before a task $v$ can be started, then there is an edge from $u$ to $v$ in the graph.

Find the order of the **tasks** so that each task can be performed in the right order.

This problem can be solved if we find the **topological sorting** of the graph.

## What is Topological Sort of a Graph?
A topological sort gives the order in which to perform the tasks. 

Topological sorting for **Directed Acyclic Graph (DAG)** is a linear ordering of vertices. For every directed edge $\{u,v\}$ vertex $u$ comes before $v$ in the ordering. 

> Topological sorting for a graph is not possible if the graph is not a **DAG**.

The algorithm for topological sorting can be visualized as follows:

Given a graph, return a list containing nodes the of the graph in topological order.

Recursion Fundamentals

Iteration Vs. Recursion

Recursion with Numbers

Recursion with Strings

Recursion with Arrays

Recursion with Data Structures

Conclusion

Challenge 3: Topological Sorting of a Graph

Problem Statement