juniorFibonacci Series
What is the space complexity of iterative Fibonacci?
Updated Apr 28, 2026
Short answer
O(1) if only storing the last two variables.
Deep explanation
The Fibonacci sequence is defined by the recurrence relation $F_n = F_{n-1} + F_{n-2}$. O(1) if only storing the last two variables.
Real-world example
Modeling population growth in ideal conditions.
Common mistakes
- Using a 1-based index when the interviewer expects 0-based.
Follow-up questions
- What is the 5th Fibonacci number?