Find the nth Fibonacci Number

Instructions

Write a function that returns the nth number in the Fibonacci sequence. The Fibonacci sequence is defined as follows:

F(0) = 0
F(1) = 1
F(n) = F(n-1) + F(n-2) for n > 1

Examples

Here are a few examples to illustrate how the fibonacci function works:

Example 1

Input: n = 1 Output: 1

Example 2

Input: n = 5 Output: 5

Example 3

Input: n = 10 Output: 55

The example solution provided demonstrates a function called fibonacci that returns the nth number in the Fibonacci sequence. The function uses a loop to calculate the sequence iteratively, storing the previous two numbers and updating them as it progresses through the sequence.

Find Fibonacci

  const fibonacci = (n) => {
    if (n < 0) return null;
    if (n === 0) return 0;
    if (n === 1) return 1;

    let a = 0, b = 1, i = 2;

    while (i <= n) {
      let temp = a + b;
      a = b;
      b = temp;
      i++;
    }

    return b;
  }