40 lines
910 B
Markdown
40 lines
910 B
Markdown
## Fibonacci Number
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Write a function called `fibonacci` that takes a non-negative integer `n` as input and returns the **n-th Fibonacci number**.
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The Fibonacci sequence is defined as:
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* `F(0) = 0`
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* `F(1) = 1`
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* `F(n) = F(n-1) + F(n-2)` for `n > 1`
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### Function Signature:
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```python
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def fibonacci(n):
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# return your solution
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```
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#### Requirements
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* The function should return the `n`-th number in the Fibonacci sequence.
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* If `n` is less than `0`, print `"Incorrect input"`.
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* Your function will be tested with:
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* Base cases (`n = 0` and `n = 1`)
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* Small values of `n`
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* Larger values of `n` (e.g., 9)
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* Multiple test cases in sequence
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#### Example:
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```python
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fibonacci(0) # returns 0
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fibonacci(1) # returns 1
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fibonacci(2) # returns 1
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fibonacci(3) # returns 2
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fibonacci(5) # returns 5
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fibonacci(9) # returns 34
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```
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You can copy this into your problem’s solution description. |