Hello reader!
I came across this problem and I'm not sure how to approach it. Any hints would be appreciated!
Problem:
The Fibonacci sequence is defined as F(0) = 1, F(1) = 1, F(n) = F(n-1) + F(n-2). So: 1, 1, 2, 3, 5, 8, 13, 21, 34, ...
Given N, count the number of ways to write N as a product of Fibonacci numbers, where each factor is > 1. Order does not matter (2×4 and 4×2 are the same representation).
Example: Input: 4 2 7 40 64 Output: 1 0 2 3
Constraints: - T ≤ 50 test cases - N can be up to 10^18
I have no idea where to start. How do you approach this kind of problem?
Thank you!
update : the problem was solved
solotion 1: Top-Down DP with Memoization author MEDAAA
solution 2: Greedy + Math author:phsads
Complexity Comparison
| Approach | Time per Query | Space | Notes |
|---|---|---|---|
| DP Memoization | $$$O(\text{Fib}^2 \log N)$$$ | $$$O(\text{Fib} \log N)$$$ | More intuitive, general DP |
| Greedy + Math | $$$O(\log N)$$$ | $$$O(\text{Fib})$$$ | Faster, uses number theory |
Credits
Thanks to MEDAAA, phsads, Ahmed-Nawaz, InfiniteLoops1730, VladiG, Metall1cA, helpT27, and others for all the discussions and ideas in the comments. Really appreciate the different approaches and insights — from DP attempts to number theory explanations.




