leetcode First Missing Positive hashset简单应用

 1 public class Solution {
 2     public int firstMissingPositive(int[] A) {
 3         HashSet<Integer> hash=new HashSet<Integer>();
 4         int count=0;
 5         int sum=0;
 6         
 7         for(int i:A)
 8         {
 9             if(i>0)
10             {
11                 hash.add(i);
12             }
13         }
14          
15          int beg=1;
16          while(hash.contains(beg))
17          {
18              beg++;
19              
20              
21          }
22          
23          return beg;
24         
25        
26         
27     }
28 }