#Leetcode# 137. Single Number II
https://leetcode.com/problems/single-number-ii/
Given a non-empty array of integers, every element appears three times except for one, which appears exactly once. Find that single one.
Note:
Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?
Example 1:
Input: [2,2,3,2] Output: 3
Example 2:
Input: [0,1,0,1,0,1,99] Output: 99
代码:
class Solution { public: int singleNumber(vector<int>& nums) { int n = nums.size(); map<int, int> mp; for(int i = 0; i < n; i ++) mp[nums[i]] ++; for(int i = 0; i < n; i ++) if(mp[nums[i]] == 1) return nums[i]; } };