Number Complement

问题描述

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:

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.

题目连接

https://leetcode.com/problems/number-complement/description/

Python

python 中~操作是取补码, 此题取反

class Solution(object):
def findComplement(self, num):
"""
:type num: int
:rtype: int
"""
return num ^ int(bin(num)[2:].replace("0","1"),2)

Java

求没有前导0的正数反码值

class Solution {
public int findComplement(int num) {
String s = Integer.toBinaryString(num);
int result = 0;
for (int i = s.length() - 1; i >= 0; i--) {
if (s.charAt(i) == '0') {
result += Math.pow(2, s.length() - 1 - i);
}
}
return result;
}
}