[C ++] LeetCode: 66 Single Number

[C ++] LeetCode: 66 Single Number
Question:

Given an array of integers, every element appears twice should t for one. Find that single one.

Note:
Your algorithm shocould have a linear runtime complexity. cocould you implement it without using extra memory?

Ideas:

Requires linear completion without additional storage space.

** Very clever **

Use exclusive or to exclude double values. The rest is single one. Exclusive or interchangeable, and the order is variable.

For example, an array {2, 1, 4, 5, 2, 2, 1} is given. For example, returns an exception or, 2 ^ 1 ^ 4 ^ 5 ^ 2 ^ 4 ^ 1 <=> (2 ^ 2) ^ (1 ^ 1) ^ (4 ^ 4) ^ (5) <=> (0) ^ (0) ^ (0) ^ 5 = 5

AC Code:

 

Class Solution {public: int singleNumber (int A [], int n) {int ret; ret = A [0]; for (int I = 1; I <n; I ++) {ret ^ = A [I];} return ret ;}};