如題
x = 0 -> (x+1)=1 -> (x+1)&1 = 1
x = 1 -> (x+1)=2 -> (x+1)&1 = 0
2 = 0b10 -> 0b10 & 0b01 = 0
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x=0 -> x^1 = 1
x=1 -> x^1 = 0