260. Single number III [Medium] (Python)

Topic links

https://leetcode.com/problems/single-number-iii/

Original title

Given An array of numbers nums , in which exactly-elements appear only once and all the other elements appear exactly Twice. Find the elements that appear only once.

For example:
Given nums = [1, 2, 1, 3, 2, 5] , return [3, 5] .

Note:

1. The order of the result is not important. The above example, is [5, 3] also correct.
2. Your algorithm should run in linear runtime complexity. Could implement it using only constant space complexity?

Method of Thinking

The topic requires O (1) space complexity and O (n) time complexity, limiting the use of auxiliary structures such as dict, so no longer discuss such solutions.
The topic requires finding two only occurrences of the number once, if done before: 136. Single number, you should be able to think of different or operation.
However, one time or two values can not be obtained, the thought of the final XOR or the resulting value is certainly not 0, then must have at least one bit is 1. According to whether this bit is 1, the original array can be divided into two, respectively, the total XOR of the two dials, the result is the required two number.
In addition, there are many ways to find a binary representation of 1 in a number, and the following two code provides two different methods.

Idea one

Write the code according to the ideas written above.

Code

 class solution(object):     def singlenumber(self, nums):        "" : Type Nums:list[int]: rtype:list[int] "" "res = [0,0] tmp = reduce (Operator.xor, nums) mask = tmp & (-tmp) forIinchNumsifI & mask:res[0] ^= IElse: res[1] ^= IreturnRes

Idea two

Only the XOR of a dial number, and then the total XOR value and the value will be different or can get the other one, reduce a lot of computational amount.

Code

class  solution   (object) :  def  singlenumber  :   res1 = 0  tmp = reduce (Operator.xor, nums)  mask = tmp-(TMP & (TMP-1 )) for  i in  nums: if  I & mask:res1 ^= I return  [res1, tmp ^ res1]  

PS: Write wrong or write not clear please help point out, thank you!
Reprint Please specify: http://blog.csdn.net/coder_orz/article/details/52071599

260. Single number III [Medium] (Python)