Space complexity O(1) and time complexity O(n) Many answers here have space complexity O(n)

public static int maxSubsetSum(List<Integer> arr) {
    int valueMinus1 = 0;
    int valueMinus2 = 0;
    int sum = 0;
    for (int i = 0; i < arr.size(); i += 1) {
        if (arr.get(i) <= 0) {
            valueMinus1 = valueMinus2 = Math.max(valueMinus1, valueMinus2);
        } else {
            sum = Math.max(valueMinus1, arr.get(i) + valueMinus2);
            valueMinus2 = valueMinus1;
            valueMinus1 = sum;
        }
    }
    return sum;
}