1 package Today; 2 //LeetCode:476. Number Complement 3 /* 4  Given a positive integer, output its complement number.  5  The complement strategy is to flip the bits of its binary representation. 6  7 Note: 8 The given integer is guaranteed to fit within the range of a 32-bit signed integer. 9 You could assume no leading zero bit in the integer’s binary representation.10 Example 1:11 Input: 512 Output: 213 Explanation: The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. So you need to output 2.14 Example 2:15 Input: 116 Output: 017 Explanation: The binary representation of 1 is 1 (no leading zero bits), and its complement is 0. So you need to output 0.18  */19 public class findComplement476 {20     public static int findComplement(int num) {21         int bits=0;22         int number=num;23         while(number>0){24             bits++;25             number=number>>1;26         }27         return num^(int)(Math.pow(2,bits)-1);28     }29     //study 原来有方法可以直接得到最高bit位30     public static int findComplement2(int num){31         return num^((Integer.highestOneBit(num)<<1)-1);32     }33     public static void main(String[] args) {34         //TODO Auto-generated method stub35         System.out.println(findComplement(5));36         System.out.println(findComplement(1));37         System.out.println(findComplement2(5));38         System.out.println(findComplement2(1));39         40     }41 42 }