README_EN.md

961. N-Repeated Element in Size 2N Array

中文文档

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

Solutions

Python3

class Solution:
    def repeatedNTimes(self, nums: List[int]) -> int:
        s = set()
        for num in nums:
            if num in s:
                return num
            s.add(num)

Java

class Solution {
    public int repeatedNTimes(int[] nums) {
        Set<Integer> s = new HashSet<>();
        for (int num : nums) {
            if (s.contains(num)) {
                return num;
            }
            s.add(num);
        }
        return -1;
    }
}

C++

class Solution {
public:
    int repeatedNTimes(vector<int>& nums) {
        unordered_set<int> s;
        for (auto &num : nums) {
            if (s.find(num) != s.end()) {
                return num;
            }
            s.insert(num);
        }
        return -1;
    }
};

JavaScript

/**
 * @param {number[]} nums
 * @return {number}
 */
var repeatedNTimes = function (nums) {
    const s = new Set();
    for (const num of nums) {
        if (s.has(num)) {
            return num;
        }
        s.add(num);
    }
    return -1;
};

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