leetcode-476-Number-Complement

描述


Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.

Note:

  1. The given integer is guaranteed to fit within the range of a 32-bit signed integer.
  2. You could assume no leading zero bit in the integer’s binary representation.

Example 1:

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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:

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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.

分析


给定一个整数,要求我们求其补数,把这个数的二进制表示翻过来就行了,如果是使用 ~ 运算会有个问题,最高位1前面的0也会被翻转,在 Java 里,使用 highestOneBit(i) 函数可以取 i 的二进制形式的最左边的最高位,其他位补零,将其减一再与 ~ 运算后的数进行与运算即为我们想要的结果。

解决方案1(Java)


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class Solution {
public int findComplement(int num) {
return ~num & (Integer.highestOneBit(num) - 1);
}
}

题目来源