2648. Generate Fibonacci Sequence

Problem

Write a generator function that returns a generator object which yields the fibonacci sequence.

The fibonacci sequence is defined by the relation Xn = Xn-1 + Xn-2.

The first few numbers of the series are 0, 1, 1, 2, 3, 5, 8, 13.

Example 1:

Input: callCount = 5
Output: [0,1,1,2,3]
Explanation:
const gen = fibGenerator();
gen.next().value; // 0
gen.next().value; // 1
gen.next().value; // 1
gen.next().value; // 2
gen.next().value; // 3

Example 2:

Input: callCount = 0
Output: []
Explanation: gen.next() is never called so nothing is outputted

Constraints:

• 0 <= callCount <= 50

Solution (Javascript)

/**
 * @return {Generator<number>}
 */
var fibGenerator = function* () {
  let prev = 0;
  let curr = 1;

  yield prev; // Yield the initial value 0
  yield curr; // Yield the initial value 1

  for (let i = 2; i <= 50; i++) {
    const next = prev + curr;
    yield next; // Yield the next Fibonacci number
    prev = curr;
    curr = next;
  }
};

/**
 * const gen = fibGenerator();
 * gen.next().value; // 0
 * gen.next().value; // 1
 */

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).