树-层次遍历

  1 package com.charles.algorithm;
  2 
  3 import java.util.LinkedList;
  4 import java.util.Queue;
  5 
  6 public class Tree {
  7 
  8     private Queue<TreeNode> elements = new LinkedList<TreeNode>();
  9 
 10     public static void main(String[] args) {
 11         /*
 12          * @desc: construct a tree:
 13          *                 root
 14          *             A            B
 15          *          C      D     E     F
 16          *        G   H  I  J
 17          */
 18 
 19         TreeNode root = new TreeNode("root");
 20 
 21         TreeNode A = new TreeNode("A");
 22         TreeNode B = new TreeNode("B");
 23         TreeNode C = new TreeNode("C");
 24         TreeNode D = new TreeNode("D");
 25         TreeNode E = new TreeNode("E");
 26         TreeNode F = new TreeNode("F");
 27         TreeNode G = new TreeNode("G");
 28         TreeNode H = new TreeNode("H");
 29         TreeNode I = new TreeNode("I");
 30         TreeNode J = new TreeNode("J");
 31 
 32         root.setLeft(A);
 33         root.setRight(B);
 34         A.setLeft(C);
 35         A.setRight(D);
 36         B.setLeft(E);
 37         B.setRight(F);
 38         C.setLeft(G);
 39         C.setRight(H);
 40         D.setLeft(I);
 41         D.setRight(J);
 42 
 43         Tree tree = new Tree();
 44         tree.broadTraval(root);
 45     }
 46 
 47     public void broadTraval(TreeNode root) {
 48 
 49         if (null != root) {
 50             elements.add(root);
 51         } else {
 52             return;
 53         }
 54 
 55         while (0 < elements.size()) {
 56             root = elements.poll();
 57             System.out.println(root.getData());
 58             if (null != root.getLeft()) {
 59                 elements.add(root.getLeft());
 60             }
 61             if (null != root.getRight()) {
 62                 elements.add(root.getRight());
 63             }
 64         }
 65     }
 66 }
 67 
 68 class TreeNode {
 69     /*
 70      * @Desc: define a tree node
 71      */
 72 
 73     private String data;
 74     private TreeNode left;
 75     private TreeNode right;
 76 
 77     public TreeNode() {
 78     }
 79 
 80     public TreeNode(String data) {
 81         super();
 82         this.data = data;
 83     }
 84 
 85     public String getData() {
 86         return data;
 87     }
 88 
 89     public void setData(String data) {
 90         this.data = data;
 91     }
 92 
 93     public TreeNode getLeft() {
 94         return left;
 95     }
 96 
 97     public void setLeft(TreeNode left) {
 98         this.left = left;
 99     }
100 
101     public TreeNode getRight() {
102         return right;
103     }
104 
105     public void setRight(TreeNode right) {
106         this.right = right;
107     }
108 }