https://leetcode.com/problems/lengthoflongestfibonaccisubsequence/
A sequence X_1, X_2, ..., X_n
is fibonaccilike if:

n >= 3

X_i + X_{i+1} = X_{i+2}
for all i + 2 <= n
Given a strictly increasing array A
of positive integers forming a sequence, find the length of the longest fibonaccilike subsequence of A
. If one does not exist, return 0.
(Recall that a subsequence is derived from another sequence A
by deleting any number of elements (including none) from A
, without changing the order of the remaining elements. For example, [3, 5, 8]
is a subsequence of [3, 4, 5, 6, 7, 8]
.)
Example 1:
Input: [1,2,3,4,5,6,7,8]
Output: 5
Explanation:
The longest subsequence that is fibonaccilike: [1,2,3,5,8].
Example 2:
Input: [1,3,7,11,12,14,18]
Output: 3
Explanation:
The longest subsequence that is fibonaccilike:
[1,11,12], [3,11,14] or [7,11,18].