Stuff

    public int equalSum(){        if(_arr == null || _arr.length == 1)            return -1;        int arSum = sum(0);        if(arSum%2 == 1)            return -1;        return equalSum(0,arSum/2 , 0);    }        private int sum(int i){        if (i>= _arr.length)            return 0;        return (_arr[i] + sum(i+1));    }        private int equalSum(int cur, int halfSum, int priorSum){        priorSum = priorSum+_arr[cur];        if(priorSum > halfSum)            return -1;        if(priorSum == halfSum)            return cur;        return equalSum(cur+1, halfSum, priorSum);    }