题目

https://www.nowcoder.com/practice/8cc4f31432724b1f88201f7b721aa391?tpId=190&&tqId=35388&rp=1&ru=/ta/job-code-high-rd&qru=/ta/job-code-high-rd/question-ranking

import java.util.*;


public class Solution {
    /**
     * return the min number
     * @param arr int整型一维数组 the array
     * @return int整型
     */
    public int minNumberdisappered (int[] arr) {
        // write code here
        int mix = 1;
        Arrays.sort(arr);
        List<Integer> list = new ArrayList<>();
        for(int i = 0 ; i < arr.length ; i++){
            list.add(arr[i]);
        }
        for(int i=1 ;; i++){
            if(!list.contains(i)){
                mix = i;
                break;
            }
        }
        return mix;
    }
}