single-number.java

/**
 * Given a non-empty array of integers, every element appears twice except for
 * one. Find that single one.
 * 
 * Note:
 * 
 * Your algorithm should have a linear runtime complexity. Could you implement
 * it without using extra memory?
 * 
 * Example 1:
 * 
 * Input: [2,2,1] Output: 1
 * 
 * Example 2:
 * 
 * Input: [4,1,2,1,2] Output: 4
 *
 */
class Solution {
	public int singleNumber(int[] nums) {
		int aloneNum = nums[0];

		for (int i = 1; i < nums.length; i++) {
			aloneNum ^= nums[i];
			// System.out.println(aloneNum);
		}

		return aloneNum;
	}
}