Subarray with 0 sum

Given an array of positive and negative numbers. Find if there is a subarray (of size at-least one) with 0 sum.

Example 1:
Input:
5
4 2 -3 1 6
Output:
Yes
Explanation:
2, -3, 1 is the subarray
with sum 0.

This is similar to the previous question Subarray sum equals k but this is EASY compared to that.

To solve this question click here:(https://practice.geeksforgeeks.org/problems/subarray-with-0-sum-1587115621/1/)

Approach 1:
Time Complexity: O(n^2)

JAVA CODE

public static boolean subArrayExists(int arr[],int n)
    {
        for(int i=0;i<n;i++)
        {
            int sum=0;
            for(int j=i;j<n;j++)
            {
                sum+=arr[j];
                if(sum==0)
                  return true;

            }
        }
        return false;
    }

Approach 2:
This is similar to the previous subarray question that we solved.
Time Complexity: O(n)

JAVA CODE

  static boolean findsum(int arr[],int n)
    {
        //Your code here
        HashMap<Integer,Integer> hm=new HashMap<>();
        hm.put(0,1); // it is imp to put 0 initially in the hashmap
        int sum=0;
        for(int i=0;i<n;i++)
        {
            sum+=arr[i];
            if(hm.containsKey(sum))
                return true;

            hm.put(sum,hm.getOrDefault(sum,0)+1);
        }
        return false;
    }

Approach 3:
We have used HashSet in this as their is no need to use HashMap since we have no use of storing values in key, pair
Time Complexity: O(n)

JAVA CODE

public static boolean subArrayExists(int arr[],int n)
    {
         //declare a set data structure
         HashSet<Integer> res=new HashSet<>();
         int sum=0;

         for(int i=0;i<n;i++)
         {
             res.add(sum);//in first step it will add 0
             sum+=arr[i];
             if(res.contains(sum))
                 return true;
         }
         return false;

    }