Bit Manipulation

Bit Manipulation

常用operators:
~        unary bitwise complement operator, inverts a bit pattern
<<       signed left shift operator
>>       signed right shift operator
>>>     unsigned right shift operator, a zero into the leftmost position
&        bitwise AND
^         bitwise exclusive OR   (必须有且只有一个为真才行）
|          bitwise inclusive OR

特性：
（n&(n-1) == 0) true if n is power of 2. (or if n=1)
  n^n = 0
可以用来判断两个词有没有重复字符

常见问题：
Leetcode 136 - Single Number
Leetcode 268 - Missing Number
Leetcode 318 - Maximum Product of Word Lengths