Binary Search Tree Iterator LeetCode solution in Java

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class BSTIterator {
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  TreeNode root;
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  TreeNode current;
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  Stack<TreeNode> st = new Stack<>();
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  public BSTIterator(TreeNode root) {
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    this.root = root;
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    // init(root);
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    current = findLeft(root);
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    // System.out.println("Init: stack is: "+st);
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  }
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  public int next() {
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    int val = -1;
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    if (current != null) val = current.val;
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    else return -1;
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    if (current.right != null) current = findLeft(current.right);
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    else if (!st.isEmpty()) current = st.pop();
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    else current = null;
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    // System.out.println("next: stack is: "+st);
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    return val;
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  }
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  public TreeNode findLeft(TreeNode node) {
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    if (node == null) return null;
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    if (node.left != null) {
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      TreeNode next = node.left;
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      st.push(node);
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      return findLeft(next);
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    } else return node;
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  }
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  public boolean hasNext() {
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    return current != null;
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  }
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}