Find the missing elements in a sequence using XOR

Find the missing number in a sequence using XOR method.

Input: 1,2,3,4,5,6,7,8,9,11,12,13,14,15

Output: 10


Solution: 

Java

int[] arr = new int[]{1,2,3,4,5,6,7,8,9,11,12,13,14,15};
int sum = arr.length*(arr.length+1)/2;
// sum=120;
//System.out.println(sum);
int val = sum;
for(int i=0;i val = val^arr[i];
}
System.out.println(val^sum);