LeetCode-in-Java

2648. Generate Fibonacci Sequence

Easy

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:

Solution

function* fibGenerator(): Generator<number, any, number> {
    let first = 0
    let second = 1
    let value = 0
    let count = 0
    while (true) {
        if (count <= 1) {
            count++
            yield value++
        } else {
            value = first + second
            first = second
            second = value
            yield value
        }
    }
}

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

export { fibGenerator }