Longest Oscillating Sub-sequence Naive

los.py

def los(A,k):
    """Auxiliary function for additional parameter k"""
    if len(A) < 2: return 0

    plusOrMinus = lambda x, y: abs(x, y) < 2

    # don't take element 0
    m = las(A[1:], k)

    # take element 0
    if plusOrMinus(A[0], k): m = max(m, 1 + las(A[1:], A[0]))

    return m

def longest_oscillating_subsequence(A):
    """Naive approach to find longest increasing sub-sequence s.t.  every
    element is +/-1 of previous"""

    if not A: return 0

    return los(A,A[0])