Longest Subarray with Zero Sum

LongestZeroSum.java

public class ZeroSum {
    
    /*
     * @param input - integer array
     * return - longest zero sum subarray list  
    */ 
    public int[] zeroSumLongest(int[] input) {
        
        Map<Integer, Integer> lookUpMap = new HashMap<>();
        int runningSum =0;
        int[] zeroSumArray = new int[]{};
        
        for(int i =0; i<input.length; i++) {
            
            runningSum +=input[i];

            int[] currentSumArray = new int[]{};
            if(runningSum==0){
                // if the sum up to this point becomes zero then this is the zero sum array
                currentSumArray = Arrays.copyOfRange(input, 0, i+1);    
            }
            else if(lookUpMap.containsKey(runningSum)) {
                // if the sum is repeated that means we already have an enclosed subrray that can be summed up to zero
                currentSumArray = Arrays.copyOfRange(input, lookUpMap.get(runningSum)+1, i+1);
            }
                
            // up date the maximum zero sum arrau
            if(zeroSumArray.length < currentSumArray.length){
                zeroSumArray = currentSumArray;
            }
                
            lookUpMap.put(runningSum, i);
        }
        
        return zeroSumArray;         
    }
}