HackerRank 'Is Fibo' Solution

Martin Kysel · March 14, 2015

Short Problem Definition:

You are given an integer, N. Write a program to determine if N is an element of the Fibonacci sequence.

Is Fibo


time complexity is O(15√(ϕn−(−ϕ)−n))

space complexity is O(15√(ϕn−(−ϕ)−n))


There are two methods:

A) generate all fibonacci numbers up to N and check if the candidates are in this set.

B) There is a mathematical function that can prove whether a number is in the Fibonacci sequence in sqrt(N) time. I am not going to explain this here. Read the discussion on SO if you are interested.


def getFibo(N):
    v = [1,2]
    while v[-1] < N:
    return set(v)

def isFibo(fiboSet, value):
    if value in fiboSet:
        return "IsFibo"
    return "IsNotFibo"

if __name__ == '__main__':
    t = input()
    values = []
    for _ in xrange(t):
    fiboSet = getFibo(max(values))
    for value in values:
        print isFibo(fiboSet, value)

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