026 返回二叉树的所有叶子

1.题目
　　返回所有的叶子节点
2.程序
 1 import java.util.List;
 2 import java.util.Queue;
 3 import java.util.LinkedList;
 4 
 5 public class Leaf {
 6     //定义树节点
 7     public static class TreeNode{
 8         TreeNode left=null;
 9         TreeNode right=null;
10         int value;
11         TreeNode(int value){
12             this.value=value;
13         }
14         @Override
15         public String toString() {
16             return "<TreeNode value:"+ this.value+">";
17         }
18     }
19     //遍历叶子节点
20     public List<TreeNode> getLeaf(TreeNode root){
21         List<TreeNode> result=new LinkedList();
22         Queue<TreeNode> nodeQueue=new LinkedList();
23         TreeNode node=null;
24         nodeQueue.add(root);
25         while(!nodeQueue.isEmpty()){
26             node=nodeQueue.poll();
27             if(node.left==null){
28                 if(node.right==null){
29                     result.add(node);
30                 }else{
31                     nodeQueue.add(node.right);
32                 }
33             }else{
34                 nodeQueue.add(node.left);
35                 if(node.right!=null){
36                     nodeQueue.add(node.right);
37                 }
38             }
39         }
40         return result;
41     }
42 
43     //主函数，用于测试
44     public static void main(String[] args){
45         TreeNode root=new TreeNode(0);
46         root.left=new TreeNode(1);
47         root.right=new TreeNode(2);
48         root.left.left=new TreeNode(3);
49         root.left.right=new TreeNode(4);
50         root.right.left=new TreeNode(5);
51         root.right.right=new TreeNode(6);
52         Leaf leaf=new Leaf();
53         System.out.println(leaf.getLeaf(root));
54     }
55 }