Zigzag max min of sorted array including negative numbers

max_min_zigzag_array.py

def max_min_negative(lst, n, new_min, new_max):
    res = []
    for i in range(n//2):
        min_idx = i
        max_idx = n-i-1
        res += [lst[max_idx], lst[min_idx]]
    if n%2 == 1:
        res[n-1] = lst[n//2]
    return res

def max_min(lst):
    if not lst:
        return lst
    n = len(lst)
    new_min, new_max = 0, n-1
    if any(i < 0 for i in lst):
        return max_min_negative(lst, n, new_min, new_max)
    maxNum = lst[-1] + 1
    for idx in range(n):
        if idx%2 == 0:  #max place
            lst[idx] += (lst[new_max] % maxNum) * maxNum
            new_max -= 1
        else:  #min place
            lst[idx] += (lst[new_min] % maxNum) * maxNum
            new_min += 1
    for idx in range(n):
        lst[idx] //= maxNum
    return lst