To solve the problem of calculating the nth Fibonacci number, we can use several approaches. The most efficient ones in terms of time complexity for large values of
- Base Cases: Define the base cases for
$F(0)$ and$F(1)$ . - Iterative Calculation: Use an iterative approach to calculate
$F(n)$ by storing the previous two Fibonacci numbers and updating them iteratively.
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Time complexity:
$O(n)$ , where$n$ is the input number. We iterate from 2 to$n$ once. -
Space complexity:
$O(1)$ , since we are using a constant amount of extra space (only a few variables for the calculations).