# Finding Number Complements using Java

## The problem

Given a positive integer num, output its complement number. The complement strategy is to flip the bits of its binary representation.

Example 1:

Input: num = 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: num = 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.

Constraints:

• The given integer num is guaranteed to fit within the range of a 32-bit signed integer.
• num >= 1
• You could assume no leading zero bit in the integer’s binary representation.

## The code

// Our method that takes in an `int` and returns an `int` public int findComplement(int num) { // Duplicate the input for reference int originalNum = num; // Set a variable for looping on an index long i = 1; // Loop while `i` is less or equal to `originalNum` while(i<=originalNum) { // Shift the variables num ^= i; i <<= 1; } // Return the resultant `num` return num; }
Code language: Java (java)
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