LeetCode之Number Complement

1、题目

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.
  
 

2、代码实现

      public class Solution {
       public int findComplement(int num) {
       if (num <= 0)
      return 0;
      String result = "";
      while (num > 0) {
       result += num % 2;
       num = num / 2;
       }
       int length = result.length();
       int lastResult = 0;
       for (int i = 0; i < length - 1; ++i) {
       if (result.charAt(i) == '0') {
       int temp = (int) Math.pow(2, i);
       lastResult += temp;
       }
       }
       return lastResult;
       }
      }
  
 

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原文链接：chenyu.blog.csdn.net/article/details/69643973