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;
    }
}