原题:
Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.
Note:
The given integer is guaranteed to fit within the range of a 32-bit signed integer.
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.
题意:
给定一个正整数,输出它的补数。补数的策略是通过翻转二进位表示。
思路:
1.求出该数的二进制位数;
2.通过给定数num和相同位数的二进制数(全为1)进行异或,即可求出补数。
代码:
public class Solution {
public int findComplement(int num) {
int ans = 0;//the count of the num's bits
int temp = num;//copy of the num
while(temp != 0){
ans++;
temp /= 2;
}
return num ^ (int)(Math.pow(2,ans)-1);
}
}