PermMissingElem Codility lesson 2

PermMissingElem Codility lesson 2

import java.util.stream.IntStream;
class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        if(A.length==0){
         return 1;   
        }
        int []sorted = IntStream.of(A).sorted().toArray();
        if(sorted[sorted.length-1]!=sorted.length+1){
         return sorted.length+1;   
        }
        
        for(int index=0;index<sorted.length;index++){
            int check=index+1;
            if(sorted[index]!=check){
             return check;   
            }
        }
        
        return 0;
        
    }
}