maximum subarray whose sum equals 0

Question

An array contains both positive and negative elements, find the maximum subarray whose sum equals 0.

Answer 1

Below codes can find out every possible sub-array that has a sum being a given number, and (of course) it can find out the shortest and longest sub-array of that kind.

public static void findGivenSumSubarray(int arr[], int givenSum) {
    int sum = 0;
    int sStart = 0, sEnd = Integer.MAX_VALUE - 1;  // Start & end position of the shortest sub-array
    int lStart = Integer.MAX_VALUE - 1, lEnd = 0;  // Start & end position of the longest  sub-array

    HashMap> sums = new HashMap<>();
    ArrayList indices = new ArrayList<>();

    indices.add(-1);
    sums.put(0, indices);

    for (int i = 0; i < arr.length; i++) {
        sum += arr[i];
        indices = sums.get(sum - givenSum);
        if(indices != null) {
            for(int index : indices) {
                System.out.println("From #" + (index + 1) + " to #" + i);
            }
            if(i - indices.get(indices.size() - 1) < (sEnd - sStart + 1)) {
                sStart = indices.get(indices.size() - 1) + 1;
                sEnd = i;
            }
            if(i - indices.get(0) > (lEnd - lStart + 1)) {
                lStart = indices.get(0) + 1;
                lEnd = i;
            }
        }
        indices = sums.get(sum);
        if(indices == null) {
            indices = new ArrayList<>();
        }
        indices.add(i);
        sums.put(sum, indices);
    }

    System.out.println("Shortest sub-arry: Length = " + (sEnd - sStart + 1) + ", [" + sStart + " - " + sEnd + "]");
    System.out.println("Longest  sub-arry: Length = " + (lEnd - lStart + 1) + ", [" + lStart + " - " + lEnd + "]");
}