H

```
package com.thealgorithms.bitmanipulation;
/**
* This class provides a method to find the element that appears an
* odd number of times in an array. All other elements in the array
* must appear an even number of times for the logic to work.
*
* The solution uses the XOR operation, which has the following properties:
* - a ^ a = 0 (XOR-ing the same numbers cancels them out)
* - a ^ 0 = a
* - XOR is commutative and associative.
*
* Time Complexity: O(n), where n is the size of the array.
* Space Complexity: O(1), as no extra space is used.
*
* Usage Example:
* int result = NumberAppearingOddTimes.findOddOccurrence(new int[]{1, 2, 1, 2, 3});
* // result will be 3
*
* @author Lakshyajeet Singh Goyal (https://github.com/DarkMatter-999)
*/
public final class NumberAppearingOddTimes {
private NumberAppearingOddTimes() {
}
/**
* Finds the element in the array that appears an odd number of times.
*
* @param arr the input array containing integers, where all elements
* except one appear an even number of times.
* @return the integer that appears an odd number of times.
*/
public static int findOddOccurrence(int[] arr) {
int result = 0;
for (int num : arr) {
result ^= num;
}
return result;
}
}
```