Fibonachchi sonmi

Butun son N > 1 berilgan. U Fibonachchi ketma-ketligiga (1, 1, 2, 3, 5, 8, …) tegishli bo'lsa true, aks holda false qaytaring.

func isFibonacci(N int) bool {
    // ...
}

Misollar

Input: N=8
Output: true

Input: N=10
Output: false

Input: N=21
Output: true

Maslahatlar

1. a, b := 1, 1 dan boshlab b < N bo'lguncha a, b = b, a+b qiling.
2. Tugagach b == N bo'lsa, son Fibonachchi soni.