I did a code that take as input integers, for example: 123 11 200 1 100 150 2000 and need to output a binary tree, in this form:

      ┌1
   ┌11┤
   │  └100
123┤
   │   ┌150
   └200┤
       └2000

but in my code output is:

0┐
 │      ┌1 
 │   ┌11┤
 │   │  └100 
 └123┤
     │   ┌150 
     └200┤
         └2000

At he root appear a zero and I do not know why. This is my code. I consider that the problem is in the add() method, but do not know how to solve it. I will be grateful for help.

    public class TreeNode extends BinaryTree implements PrintableTree {
    private int i;
    private TreeNode leftChild;
    private TreeNode rightChild;

    public TreeNode(int i) {
        this.i = i;
    }

    public TreeNode() {

    }

    @Override
    public void add(int i) {
        if (i > this.i) {
            if (this.rightChild == null) {
                this.rightChild = new TreeNode(i);
            } else {
                this.rightChild.add(i);
            }
        } else {
            if (this.leftChild == null) {
                this.leftChild = new TreeNode(i);
            } else {
                this.leftChild.add(i);
            }
        }
    }

    public int getI() {
        return i;
    }

    public void setLeftChild(TreeNode leftChild) {
        this.leftChild = leftChild;
    }

    public void setRightChild(TreeNode rightChild) {
        this.rightChild = rightChild;
    }

    public TreeNode getLeftChild() {
        return leftChild;
    }

    public TreeNode getRightChild() {
        return rightChild;
    }



    @Override
    public String prettyPrint() {

        StringBuilderPlus builder = new StringBuilderPlus();
        prettyPrint(builder, "", "", "", "");

        return builder.toString();
    }

   public void print() {
       StringBuilderPlus res = new StringBuilderPlus();
       prettyPrint(res, "", "", "", "");
    }

    public void prettyPrint(StringBuilderPlus result, String prefix, String left, String mid, String right) {
        String indent = " ".repeat(String.valueOf(i).length());
        if (leftChild != null) {
            leftChild.prettyPrint(result, prefix   left   indent, " ", "┌", "│");
        }
        result.appendLine(prefix   mid   i
                  " ┐┘┤".charAt((leftChild != null ? 2 : 0)
                  (rightChild != null ? 1 : 0)));
        if (rightChild != null) {
            rightChild.prettyPrint(result, prefix   right   indent, "│", "└", " ");
        }
    }
}
public class StringBuilderPlus {

    private StringBuilder sb;

    public StringBuilderPlus(){
        sb = new StringBuilder();
    }

    public void append(String str)
    {
        sb.append(str != null ? str : "");
    }

    public void appendLine(String str)
    {
        sb.append(str != null ? str : "").append(System.getProperty("line.separator"));
    }

    public String toString()
    {
        return sb.toString();
    }
}
class BinaryTree {
    private TreeNode root;

    public void Print() {
        if (root != null) {
            root.print();
        }
    }

    public void add(int i) {
        if (root == null) {
            root = new TreeNode(i);
        } else {
            root.add(i);
        }
    }
}
public interface PrintableTree {

    void add(int i);
    String prettyPrint();

    static PrintableTree getInstance() {
        return new TreeNode();
    }
}

CodePudding user response：

Thank you for posting the rest of the code. Your issue is with the PrintableTree interface in method getInstance. You return a new TreeNode (it comes initialized with 0 as int is a primitive type and cannot be null). And then you add the rest of the nodes to that original node with 0. You most likely wanted to return a new BinaryTree instead. However you need to change your code as BinaryTree does not implement the PrintableTree interface.

Here are the changes necessary to fix it:

In PrintableTree.java

static PrintableTree getInstance() {
    return new BinaryTree();
}

In BinaryTree.java

// notice the added implements
class BinaryTree implements PrintableTree {
// the rest of the class is fine, add this to the end
    @Override
    public String prettyPrint() {
        if (root != null) {
            return root.prettyPrint();
        }
        return "";
    }
}

Also the class TreeNode does not need to extend BinaryTree as a node is not a tree (it doesn't make sense for the node the contain a value AND a root). If your assignment requires this relation then edit the code accordingly.

CodePudding user response：

Need more info. The code you've posted looks correct. My guess would be something in the main method.