Understanding the problem

To better understand graphs, we must consider some of the challenges programmers face when designing software systems. A data structure is primarily used to store and retrieve data efficiently. All linear data structures store data sequentially, like arrays, linked lists, stacks, and queues. On the other hand, tree data structures, like binary trees and heaps, store data hierarchically. 

When designing solutions to complex problems, we often need some way to model the relationship between multiple data items. While a tree can model parent-child relationships, it cannot model many-to-many relationships.

Travel booking problem