Task80.py

def get_rel(arr, i, i1 = -1):
    if i!=0 or i1!=-1:
        if i1==-1:
            i1 = i-1
        if arr[i]>arr[i1]:
            return +1
        elif arr[i]<=arr[i1]:
            return -1
        else:
            return 0

def check_node(arr, i, c_i, rel):
    c_rel = get_rel(arr, c_i)
    if c_rel!=rel:
        cc_rel = get_rel(arr, i, c_i-1)
        return c_rel==cc_rel
    return True

def task80(arr):
    for i in range(1, len(arr)):
        rel = get_rel(arr, i)
        for c_i in range(i-1, 0, -1):
            if not check_node(arr, i, c_i, rel):
                print(False)
                return
    print(True)
    return


"""
task80([5,4,3,2,1])
task80([1,2,3,2])
task80([5,5,4,5])
"""