Longest Sub-Array with Sum K

class Solution
{
    
   
    // Function for finding maximum and value pair
    public static int lenOfLongSubarr (int a[], int n, int k) 
    {

        Map<Long, Integer> preSumMap = new HashMap<>();
        long sum = 0;
        int maxLen = 0;
        for (int i = 0; i < n; i++) 
        {
            
            sum += a[i];
            
            if (sum == k) 
            {
                maxLen = Math.max(maxLen, i + 1);
            }

            
            long rem = sum - k;

            
            if (preSumMap.containsKey(rem)) 
            {
                int len = i - preSumMap.get(rem);
                maxLen = Math.max(maxLen, len);
            }

            
            if (!preSumMap.containsKey(sum)) 
            {
                preSumMap.put(sum, i);
            }
        }

        return maxLen;
    
        
    }
    
    
}