LC 961. N-Repeated Element in Size 2N Array【签到题】

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:

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

 

 

class Solution {
public:
    int repeatedNTimes(vector<int>& A) {
        map<int,int> m;
      for(int i=0; i<A.size(); i++){
        if(m.count(A[i])) return A[i];
        m[A[i]] = i;
      }
    }
};