异或运算
1^1 = 0 0^0 = 0 1^0 = 1
交换律 ：交换任何运算元素的位置，结果不变 a^b^a = a^a^b = 0^b = 0
a^b^a = a^a^b = 0^b = 0
结合律：(a^b)^c = a^(b^c)
(a^b)^c = a^(b^c)
对于任何x，都有 x^x = 0, x^0 = x,同自己求异或等于0，同0求异或等于自身
x^x = 0
x^0 = x
自发性：a^b^b = a^0 = a,连续同一个元素做异或运算等于自身
a^b^b = a^0 = a
