整数反转

def reverse_integer(integer):
    # over range, return zero
    if integer < -2**32 or integer > 2**32-1:
        return 0
    # negative number
    flag = 1
    if integer < 0:
        flag = -1
        integer = abs(integer)
    # reverse integer
    s = 0
    while True:
        s *= 10

        r = integer%10
        integer = integer//10

        s += r
        if integer == 0:
            break
    
    return flag*s

x = -123
y = reverse_integer(x)
print(x, y)

s = 120
t = reverse_integer(s)
print(s, t)

s = 123
t = reverse_integer(s)
print(s, t)