Question

假设我在树中有一个节点，我怎样才能获得其祖先是这个节点的所有叶子节点？我已经像这样定义了TreeNode：

public class TreeNode<T>
{
    /** all children of the node */
    private List<TreeNode<T>> children = new ArrayList<TreeNode<T>>();
    /** the parent of the node, if the node is root, parent = null */
    private TreeNode<T> parent = null;
    /** the stored data of the node */
    private T data = null;

    /** the method I want to implement */
    public Set<TreeNode<T>> getAllLeafNodes()
    {
        Set<TreeNode<T>> leafNodes = new HashSet<TreeNode<T>>();
        return leafNodes;
    }
}

Answer 1

使用递归。

如果节点本身是叶子，则将其返回
否则，返回其子节点的所有叶节点

像这样（未经测试）：

public Set<TreeNode<T>> getAllLeafNodes() {
    Set<TreeNode<T>> leafNodes = new HashSet<TreeNode<T>>();
    if (this.children.isEmpty()) {
        leafNodes.add(this);
    } else {
        for (TreeNode<T> child : this.children) {
            leafNodes.addAll(child.getAllLeafNodes());
        }
    }
    return leafNodes;
}

Answer 2

创建一个堆栈并推送根节点。

    import React from "react";
    import { BrowserRouter } from 'react-router-dom';
    import { MDBNav, MDBNavItem, MDBNavLink } from "mdbreact";

    const MiTabs = props => {

    return (

      <BrowserRouter>
        <MDBNav className="nav-tabs mt-5">
        {props.data.map(a => (
          <MDBNavItem> 
   //Add a link prop to component below
             <MDBNavLink link active='true' to={a.enlace}>
                {a.nombre} 
             </MDBNavLink>  
          </MDBNavItem>
          ))}

          <MDBNavItem>
   //Add a link prop to component below
            <MDBNavLink link active to="#!">Active</MDBNavLink>
          </MDBNavItem>
          <MDBNavItem>

   //Add a link prop to component below
            <MDBNavLink link to="#!">NO Active</MDBNavLink>
          </MDBNavItem>

        </MDBNav>

      </BrowserRouter>

      );
    };

    export default  MiTabs;

调用递归方法。

public static void  main(String[] args) {

  //  System.out.println("Enter a number to changeit at char  ");
    Random random = new Random();

    int x = random.nextInt(26)+65;    //0  to 25
    System.out.println((char)x);
}

如何获取树的所有叶节点？

2 个答案: