LeetCode | Single Number

题目

Given an 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

经典的方法就是从头到尾的异或运算，这里说不要用额外空间，那么可以直接用数组元素存储计算结果。

扩展的方法可以参考Single Number II中的解法。

代码

public class SingleNumber {
	public int singleNumber(int[] A) {
		assert A != null && A.length > 0;
		for (int i = 1; i < A.length; ++i) {
			A[0] ^= A[i];
		}
		return A[0];
	}
}