LeetCode108|数组中重复的数字

示例 1：

输入：
[2, 3, 1, 0, 2, 5, 3]
输出：2 或 3 
 

限制：

2 <= n <= 100000

import java.util.Arrays;
import java.util.HashMap;

public class FindRepeatNumberTest2 {
    public static void main(String[] args) {
        int[] nums = {2, 3, 1, 0, 2, 5, 3};
        int repeatNumber = findRepeatNumber2(nums);
        System.out.println("repeatNumber = " + repeatNumber);
    }

    public static int findRepeatNumber(int[] nums) {
        if (nums == null || nums.length == 0) {
            return -1;
        }
        HashMap<Integer, Integer> hashMap = new HashMap<>(nums.length);
        for (int num : nums
        ) {
            hashMap.put(num, hashMap.getOrDefault(num, 0) + 1);
        }
        return hashMap.entrySet().stream().filter(x -> x.getValue() > 1).findFirst().get().getKey();
    }

    public static int findRepeatNumber2(int[] nums) {
        if (nums == null || nums.length == 0) {
            return -1;
        }
        Arrays.sort(nums);
        for (int i = 1; i < nums.length; i++) {
            if (nums[i] == nums[i - 1]) {
                return nums[i];
            }
        }
        return -1;
    }
}