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