Compute the Fibonacci Value at an Index
Company: Meta
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: easy
Interview Round: Other
### Problem
The sequence starts with F(0)=0 and F(1)=1. For n greater than one, F(n)=F(n-1)+F(n-2). Return F(n).
```cpp
class Solution {
public:
int fib(int n);
};
```
### Examples
**Example 1:**
```text
n = 5
Output: 5
Explanation: The values through index five are 0,1,1,2,3,5.
```
**Example 2:**
```text
n = 7
Output: 13
Explanation: F(7)=8+5.
```
### Constraints
- The sequence index n is between 0 and 30, inclusive.
### Clarifying Questions
Use the stated zero-based initial conditions and retain only the two preceding values.
```hint Read the boundary condition
Which already-computed values are needed for the next sequence term?
```
### Contract considerations
Use the stated zero-based initial conditions and retain only the two preceding values.
Overview: Compute the Fibonacci Value at an Index. The sequence starts with F(0)=0 and F(1)=1.