text: """961. N-Repeated Element in Size 2N Array
  https://leetcode.com/problems/n-repeated-element-in-size-2n-array/
  
  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.
  
  Example 1:
  
  Input: [1,2,3,3]
  Output: 3
  
  Example 2:
  
  Input: [2,1,2,5,3,2]
  Output: 2
  
  Example 3:
  
  Input: [5,1,5,2,5,3,5,4]
  Output: 5
  
  Note:
  
  4 <= A.length <= 10000
  0 <= A[i] < 10000
  A.length is even
  """
  import collections
  from typing import List
  
  
  class Solution:
      def repeated_n_times(self, a: List[int]) -> int:
          size = len(a)
          assert size % 2 == 0
          d = {}
          n = size / 2
          for i in a:
              if i in d:
                  d[i] = d[i] + 1
              else:
                  d[i] = 1
              if d[i] == n:
                  return i
  
      def ans(self, a: List[int]) -> int:
          count = collections.Counter(a)
          for k in count:
              if count[k] > 1:
                  return k
  
      def ans_2(self, a: List[int]) -> int:
          for k in range(1, 4):
              for i in range(len(a) - k):
                  if a[i] == a[i + k]:
                      return a[i]
  