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:

1. 4 <= A.length <= 10000
2. 0 <= A[i] < 10000
3. A.length is even

Solution: Randomization

Randomly pick two numbers in the array, if they are the same (25% probability) return the number, do it until the two numbers are the same.

Time complexity: O(1) expected 4
Space complexity: O(1)

// Author: Huahua, running time: 72 ms
class Solution {
public:
  int repeatedNTimes(vector<int>& A) {
    int i = 0;
    int j = 0;
    while (i == j || A[i] != A[j]) {
      i = rand() % A.size();
      j = rand() % A.size();
    }
    return A[i];
  }
};

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