Smallest Positive missing number in Java

You are given an array arr[] of N integers including 0. The task is to find the smallest positive number missing from the array.

Example 1:

Input:
N = 5
arr[] = {1,2,3,4,5}
Output: 6

Smallest Positive missing number in Java

class Solution
{
    //Function to find the smallest positive number missing from the array.
    static int missingNumber(int arr[], int size)
    {
        // Your code here
        HashMap<Integer,Integer> hm=new HashMap<Integer,Integer>();
        
        for(int i=0;i<size;i++){
            if(arr[i]>0){
                hm.put(arr[i],1);
            }
            
        } 
        for(int i=1;i<=size;i++){
            
         if(!hm.containsKey(i)) return i;
            
            
        }
        return size+1;
    }
}

Disclaimer: This problem(Smallest Positive Missing Number) is originally created by GeeksforGeeks. Codesagar only provides a solution for it. This solution is only for Educational and learning purposes.