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.

解答

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public class Solution {
	// 算法设计：容易看出num和result转化为二进制相加正好为11...1；即2的i次方-1；
	public int findComplement(int num) {
		int i = 0;
		int result = 0;
		while (Math.pow(2, i) <= num) {
			result += Math.pow(2, i);
			i++;
		}
		return (result - num);
	}
}