Kadanes Ordered Set

int maxSubarraySum(int[] arr) {

        int maxSum = Integer.MIN_VALUE;
        int prefixSum = 0;

        TreeSet<Integer> set = new TreeSet<>();

        set.add(0);

        for(int el: arr) {
            prefixSum += el;

            maxSum = Math.max(maxSum, prefixSum - set.first());

            set.add(prefixSum);
        }

        return maxSum;
    }