Introduction to Data Structures
What data structures are, why they matter, and how to choose the right one.
What is a Data Structure?
A data structure is a way of organising and storing data so that it can be accessed and modified efficiently. The right structure can turn a slow program into a fast one â choosing wisely is often more important than optimizing code line by line.
Linear vs Non-Linear
Linear structures (arrays, linked lists, stacks, queues) arrange data sequentially. Non-linear structures (trees, graphs) allow data to branch and connect in more complex ways, better representing hierarchical or networked relationships.
How to Choose
Ask: do you need fast lookups (hash maps), ordered data (arrays/trees), fast insertion/deletion (linked lists), or relationships between items (graphs)? The answer usually points you to the right structure.
đ Real-World Use
When you open an app and see a friend list, it's stored as an array or list. When you see 'People You May Know', it's a graph. When Instagram shows your feed in order of posting time, that's a queue-like structure. Every app you use is a combination of data structures working together.
đĄ Pro Tip
In interviews, before writing code, always say out loud: 'I'll use a hashmap here for O(1) lookup' â explaining WHY you picked a structure impresses interviewers more than the code itself.
đ§Ē Quick Self-Test
Check what you just learned â no pressure, just practice.
1. Which of these is a non-linear data structure?
2. Why does choosing the right data structure matter?