void go(Map<Integer, Integer> map, TreeNode root){
        if(root==null)return;
        map.put(root.val, map.getOrDefault(root.val, 0)+1);
        go(map, root.left);
        go(map, root.right);
    }
Why Did you create this class? what does it do?
src/problems/easy/TwoSumIVInputisaBST.java