[leetcode] 961. N-Repeated Element in Size 2N Array

Description

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

分析

题目的意思是：给你一个数组，找出其中一个出现N次的数，我的做法很简单，既然知道了这个数出现了N次，所以只要统计找到第一个频率为N的数就是所求的元素了。

代码

class Solution:
    def repeatedNTimes(self, A: List[int]) -> int:
        d=defaultdict(int)
        N=len(A)//2
        for ch in A:
            d[ch]+=1
            if(d[ch]==N):
                return ch