Bit ManipulationXORArray
In an array every value appears exactly twice, except for one value that appears once. Find that single value. Aim for linear time and constant extra space.
Input
Line 1: n (always odd). Line 2: n integers.
Output
Print the value that appears once.
Constraints
1 <= n <= 10^5, n is odd -3 * 10^4 <= each value <= 3 * 10^4
Example 1
Input
5 4 1 2 1 2
Output
4
1 and 2 cancel in pairs; 4 remains.