reverse.py

"""
f(1) = -1
f(-1) = 1
"""

def f1(x):
    return -x


def f2(x):
    return 1 if len(str(x)) > 1 else -1


def f3(x):
    arr = [None, -1, 1]
    return arr[x]


def f4(x):
    s = set([1, -1])
    s.remove(x)
    return list(s)[0]


def f5(x):
    return (x ^ -1) + 1