Find Elements in a Contaminated Binary Tree LeetCode solution in Java

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class FindElements {
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  TreeNode tree, nodept;
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  public FindElements(TreeNode root) {
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    tree = root;
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    tree.val = 0;
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    go(tree);
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  }
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  void go(TreeNode node) {
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    if (node.left != null) {
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      node.left.val = node.val * 2 + 1;
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      go(node.left);
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    }
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    if (node.right != null) {
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      node.right.val = node.val * 2 + 2;
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      go(node.right);
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    }
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  }
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  public boolean find(int target) {
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    return doit(target);
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  }
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  boolean doit(int target) {
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    if (target == 0) {
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      nodept = tree;
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      return true;
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    }
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    boolean f = doit((target - 1) / 2);
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    if (!f) return false;
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    if (nodept.left != null && nodept.left.val == target) nodept = nodept.left;
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    else if (nodept.right != null && nodept.right.val == target) nodept = nodept.right;
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    else f = false;
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    return f;
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  }
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}