Question

在过去的几天里，我一直在研究二叉树。我似乎遇到的一个任务是显示BinaryTree类的preOrderTraversal和postOrderTraversal方法。目前，我只能显示displayInOrder方法。我该怎么做才能解决这个错误？

public class BinaryTree {
BinaryTreeNode root = null;

public void insertInTree (int newData) {
    if (root == null) 
        root = new BinaryTreeNode(newData);
    else root.insert(newData);
    }


  public void displayInOrder () {
      displayInOrder (root);
  }

  public void preOrderTraversal () {
      preOrderTraversal (root);
  }

  public void postOrderTraversal () {
      postOrderTraversal (root);
  }

  public void preOrderTraversal (BinaryTreeNode subRoot) {
      if (subRoot == null) return;
      preOrderTraversal(subRoot.getLeft());
      System.out.println(" " + subRoot.getData() + " ");
      preOrderTraversal(subRoot.getRight());
  }

  public void postOrderTraversal (BinaryTreeNode subRoot) {
      if (subRoot == null) return;
      postOrderTraversal(subRoot.getLeft());
      System.out.println(" " + subRoot.getData() + " ");
      postOrderTraversal(subRoot.getRight());
  }

  public void displayInOrder (BinaryTreeNode subRoot){
        if (subRoot == null)   return;
        displayInOrder (subRoot.getLeft());
        System.out.print(" " + subRoot.getData() + " ");
        displayInOrder (subRoot.getRight());

  }


  }

public class BinaryTreeNode {
private int data;
private BinaryTreeNode left;
private BinaryTreeNode right;

public BinaryTreeNode() {
    left = null;   right = null; data = 0;
}
public BinaryTreeNode(int data) {
    left = null;   right = null; this.data = data;
}
public int getData() {
    return data;
}
public BinaryTreeNode getLeft() {
    return left;
}
public BinaryTreeNode getRight() {
    return right;
}
public void insert (int newData) {
    if (newData  <  data) {
        if (left == null)
            left = new BinaryTreeNode(newData);
        else left.insert(newData);
    } else if (newData >  data) {
        if (right == null)
            right = new BinaryTreeNode(newData);
        else right.insert(newData);
    } else 
         System.out.println("Duplicate – not adding……" + newData);
}



}




public class BinaryTreeExample {

public static void main(String[] args) {
    BinaryTree tree = new BinaryTree();

    tree.insertInTree(6);
    tree.insertInTree(3);
    tree.insertInTree(9);
    tree.insertInTree(1);
    tree.insertInTree(15);
    tree.insertInTree(7);

    tree.displayInOrder();

}

}

Answer 1

缩写遍历定义：

＆＃34;按顺序＆＃34; =左，自，右
＆＃34;预订＆＃34; =自我，左，右
＆＃34;发布订单＆＃34; =左，右，自我

将它应用到您的代码中，您只需要移动＆＃34; print self＆＃34;围绕着：

public void preOrderTraversal (BinaryTreeNode subRoot) {
    if (subRoot == null) return;
    System.out.print(" " + subRoot.getData() + " ");
    preOrderTraversal(subRoot.getLeft());
    preOrderTraversal(subRoot.getRight());
}

public void postOrderTraversal (BinaryTreeNode subRoot) {
    if (subRoot == null) return;
    postOrderTraversal(subRoot.getLeft());
    postOrderTraversal(subRoot.getRight());
    System.out.print(" " + subRoot.getData() + " ");
}

// already correct
public void displayInOrder (BinaryTreeNode subRoot){
    if (subRoot == null)   return;
    displayInOrder (subRoot.getLeft());
    System.out.print(" " + subRoot.getData() + " ");
    displayInOrder (subRoot.getRight());
}

这些方法只打印内容。您需要在包装器方法中打印最终换行符：

public void displayInOrder () {
    displayInOrder (root);
    System.out.println();
}

public void preOrderTraversal () {
    preOrderTraversal (root);
    System.out.println();
}

public void postOrderTraversal () {
    postOrderTraversal (root);
    System.out.println();
}

Java：显示前序和后序遍历

1 个答案: