LeetCode 136. Single Number

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

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

We can simply use hashmap to count every number’s count of appearing, then output the numbers only occur once.

the Code:

Github: https://github.com/tinyfool/leetcode/tree/master/src/p0136

To see more hashtable related problems, see 
Problems and Solutions of Hashmap.

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