Foundations - Big-O Notation
The language every engineer uses to describe speed - what O(n), O(log n), and friends actually measure, and why constants stop mattering.
What Big-O measures
Big-O describes how work GROWS as input grows - not how many milliseconds something takes. O(n) means 'work scales in step with n'.
O(n) means the algorithm's work…
Where you will see it
Real systems that use this exact idea. Tap a card to open it.
Common traps
The mistakes interviewers watch for. Guess the fix, then reveal it.
FixIt means constant - even a slow constant operation is O(1).
FixO(2n) is written O(n); constants never survive.
FixEngineers plan against worst case unless stated otherwise.
Interview prep
Questions you could be asked, with the depth an interviewer wants to hear.
A way to describe how an algorithm's work grows with input size, ignoring constants and hardware differences.
growth rate