Leetcode topic [array] -136- numbers that appear only once

Force link ：https://leetcode-cn.com/probl...
Their thinking ：

1. Conventional thinking ： Use hash / Set to make de duplication judgment , But space needs to be reopened , Resulting in increased spatial complexity
2. Exclusive or ： English is exclusive OR, Abbreviation xor, It has the following algorithm ：
   
   As shown above , In the title , Only one number appears only once , According to the law of Union & Commutative law & Reflexive law , Two identical numbers Exclusive or The result is 0,0 With any number Exclusive or Equal to the number itself , So all numbers and initialization numbers 0 Or , The last value is the number that appears once

func singleNumber(nums []int) int {
    single := 0
    for _, v := range nums {
        single ^= v
    }
    return single
}