[Leetcode] 476. Number Complement

Description:

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:

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.

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.

P.S.

Java 中十进制转二进制：https://www.cnblogs.com/vsign/p/7290594.html

class Solution {

    public int findComplement(int num) {
       //int t = 0;
       //int bin = 0;
       int r = 0;
       int result = 0;
       List<Integer> a = new ArrayList<Integer>();
       List<Integer> b = new ArrayList<Integer>();
       while(num != 0){
           r = num % 2;
           num = num / 2;
          //bin = r * Math().pow(10,t);
           a.add(r);
         //t++; 
      }
       for (Integer c : a){
          if (Integer.valueOf(c) == 1){
              int lin = 0;
              Integer Lin = Integer.valueOf(lin);
              b.add(Lin);
          }else {
              int yi = 1;
              Integer Yi = Integer.valueOf(yi);
              b.add(Yi);
          }       
       }
       for (int i = 0; i < b.size(); i++){
           result = result + ((int)Math.pow(2,(double)i) * Integer.valueOf(b.get(i)));//pow 中用到的(a,b) 都必须是double 类型的数据。Math.pow所有的数据类型都必须是double类型。所以需要用(double)i来先从int转换成double
       }
       return result;
    }
}