Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.
Note:
- The given integer is guaranteed to fit within the range of a 32-bit signed integer.
- You could assume no leading zero bit in the integer’s binary representation.
Example 1:
Input: 5 Output: 2 Explanation: The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. So you need to output 2.
Example 2:
Input: 1 Output: 0 Explanation: The binary representation of 1 is 1 (no leading zero bits), and its complement is 0. So you need to output 0.<Solution>
想法如下
num : 1101
mask: 11111111
因為 num 總共有四位,所以將 mask 左移四位,變成 11110000
然後將兩個都 flip
~num : 0010
~mask : 00001111
答案就會是 ~num & ~mask 了
code 如下
C++(參考解法)
Java(參考解法)
使用 Integer.highestOneBit 來找到 LMB,然後左移一位再減1,這樣就可以做出所要的 mask
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