题目：

In a array A of size 2N, there are N+1 unique elements, and exactly one of these elements is repeated N times.

Return the element repeated N times.

　实例输出：

Input: [1,2,3,3]
Output: 3
Input: [2,1,2,5,3,2]
Output: 2

本题就是一个简单的字典统计，然后找到出现了n次的数字输出就行了。

 1 class Solution:
 2     def repeatedNTimes(self, A: List[int]) -> int:
 3         dic = {}
 4         for i in A:
 5             if i in dic:
 6                 dic[i] += 1
 7             else:
 8                 dic[i] = 1
 9         for i in dic:
10             if dic[i] * 2 == len(A):
11                 return i