_961.java

package com.fishercoder.solutions;

import java.util.HashSet;
import java.util.Set;

/**
 * 961. 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
 * */
public class _961 {
    public static class Solution1 {
        public int repeatedNTimes(int[] A) {
            Set<Integer> set = new HashSet<>();
            for (int num : A) {
                if (!set.add(num)) {
                    return num;
                }
            }
            return -1;
        }
    }
}