Find the longest Arithmetic Progression in an integer array A of size N, and return its length.Problem Constraints
More formally, find longest sequence of indices, 0 < i1 < i2 < … < ik < ArraySize(0-indexed) such that sequence A[i1], A[i2], …, A[ik] is an Arithmetic Progression.
Arithmetic Progression is a sequence in which all the differences between consecutive pairs are the same, i.e sequence B, B, B, …, B[m - 1] of length m is an Arithmetic Progression if and only if B - B == B - B == B - B == … == B[m - 1] - B[m - 2]
Note: The common difference can be positive, negative, or 0.
1 <= N <= 1000Input Format
1 <= A[i] <= 1e9
The first and only argument of input contains an integer array, A.Output Format
Return an integer, representing the length of the longest possible arithmetic progression.Example Input
A = [3, 6, 9, 12]
A = [9, 4, 7, 2, 10]
[3, 6, 9, 12] form an arithmetic progression.
[4, 7, 10] form an arithmetic progression.
NOTE: You only need to implement the given function. Do not read input, instead use the arguments to the function. Do not print the output, instead return values as specified.
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