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: 5Output: 2Explanation: 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: 1Output: 0Explanation: The binary representation of 1 is 1 (no leading zero bits), and its complement is 0. So you need to output 0.
- 思路: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。
- 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。
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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); }
pow() 函数用来求 x 的 y 次幂(次方),其原型为:
double pow(double x, double y);