4003. Longest Fibonacci Subarray

Medium

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You are given an array of positive integers nums.

A Fibonacci array is a contiguous sequence whose third and subsequent terms each equal the sum of the two preceding terms.

Return the length of the longest Fibonacci subarray in nums.

Note: Subarrays of length 1 or 2 are always Fibonacci.

 

Example 1:

Input: nums = [1,1,1,1,2,3,5,1]

Output: 5

Explanation:

The longest Fibonacci subarray is nums[2..6] = [1, 1, 2, 3, 5].

[1, 1, 2, 3, 5] is Fibonacci because 1 + 1 = 2, 1 + 2 = 3, and 2 + 3 = 5.

Example 2:

Input: nums = [5,2,7,9,16]

Output: 5

Explanation:

The longest Fibonacci subarray is nums[0..4] = [5, 2, 7, 9, 16].

[5, 2, 7, 9, 16] is Fibonacci because 5 + 2 = 7, 2 + 7 = 9, and 7 + 9 = 16.

Example 3:

Input: nums = [1000000000,1000000000,1000000000]

Output: 2

Explanation:

The longest Fibonacci subarray is nums[1..2] = [1000000000, 1000000000].

[1000000000, 1000000000] is Fibonacci because its length is 2.

 

Constraints:

• 3 <= nums.length <= 105
• 1 <= nums[i] <= 109

// Add your C++ solution here

class Solution {
    public int longestSubarray(int[] nums) {
        int n = nums.length;
        int maxi = 2, current = 2;
        int a = nums[0], b = nums[1];
        for (int i = 2; i < n; i++) {
            if (a + b != nums[i]) {
                a = b;
                b = nums[i];
                current = 2;
            } else {
                current++;
                maxi = Math.max(maxi, current);
                a = b;
                b = nums[i];
            }
        }
        return maxi;
    }
}