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首先我想问为什么要用LinkedList 来建立二叉树呢? LinkedList 是线性表,
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树是树形的, 似乎不太合适。
其实也可以用数组完成，而且效率更高.
关键是我觉得你这个输入本身就是一个二叉树啊，
String input = "ABCDE F G";
节点编号从0到8. 层次遍历的话:
对于节点i.
leftChild = input.charAt(2*i+1); //做子树
rightChild = input.charAt(2*i+2);//右子树
如果你要将带有节点信息的树存到LinkedList里面, 先建立一个节点类:
class Node{
public char cValue;
public Node leftChild;
public Node rightChild;
public Node(v){
this.cValue = v;
}
}
然后遍历input,建立各个节点对象.
LinkedList tree = new LinkedList();
for(int i=0;i input.length;i++)
LinkedList.add(new Node(input.charAt(i)));
然后为各个节点设置左右子树:
for(int i=0;iinput.length;i++){
((Node)tree.get(i)).leftChild = (Node)tree.get(2*i+1);
((Node)tree.get(i)).rightChild = (Node)tree.get(2*i+2);
}
这样LinkedList 就存储了整个二叉树. 而第0个元素就是树根，思路大体是这样吧。
//******************************************************************************************************//
//*****本程序包括简单的二叉树类的实现和前序,中序,后序,层次遍历二叉树算法,*******//
//******以及确定二叉树的高度,制定对象在树中的所处层次以及将树中的左右***********//
//******孩子节点对换位置,返回叶子节点个数删除叶子节点,并输出所删除的叶子节点**//
//*******************************CopyRight By phoenix*******************************************//
//************************************Jan 12,2008*************************************************//
//****************************************************************************************************//
public class BinTree {
public final static int MAX=40;
private Object data; //数据元数
private BinTree left,right; //指向左,右孩子结点的链
BinTree []elements = new BinTree[MAX];//层次遍历时保存各个节点
int front;//层次遍历时队首
int rear;//层次遍历时队尾
public BinTree()
{
}
public BinTree(Object data)
{ //构造有值结点
this.data = data;
left = right = null;
}
public BinTree(Object data,BinTree left,BinTree right)
{ //构造有值结点
this.data = data;
this.left = left;
this.right = right;
}
public String toString()
{
return data.toString();
}//前序遍历二叉树
public static void preOrder(BinTree parent){
if(parent == null)
return;
System.out.print(parent.data+" ");
preOrder(parent.left);
preOrder(parent.right);
}//中序遍历二叉树
public void inOrder(BinTree parent){
if(parent == null)
return;
inOrder(parent.left);
System.out.print(parent.data+" ");
inOrder(parent.right);
}//后序遍历二叉树
public void postOrder(BinTree parent){
if(parent == null)
return;
postOrder(parent.left);
postOrder(parent.right);
System.out.print(parent.data+" ");
}// 层次遍历二叉树
public void LayerOrder(BinTree parent)
{
elements[0]=parent;
front=0;rear=1;
while(frontrear)
{
try
{
if(elements[front].data!=null)
{
System.out.print(elements[front].data + " ");
if(elements[front].left!=null)
elements[rear++]=elements[front].left;
if(elements[front].right!=null)
elements[rear++]=elements[front].right;
front++;
}
}catch(Exception e){break;}
}
}//返回树的叶节点个数
public int leaves()
{
if(this == null)
return 0;
if(left == nullright == null)
return 1;
return (left == null ? 0 : left.leaves())+(right == null ? 0 : right.leaves());
}//结果返回树的高度
public int height()
{
int heightOfTree;
if(this == null)
return -1;
int leftHeight = (left == null ? 0 : left.height());
int rightHeight = (right == null ? 0 : right.height());
heightOfTree = leftHeightrightHeight?rightHeight:leftHeight;
return 1 + heightOfTree;
}
//如果对象不在树中,结果返回-1;否则结果返回该对象在树中所处的层次,规定根节点为第一层
public int level(Object object)
{
int levelInTree;
if(this == null)
return -1;
if(object == data)
return 1;//规定根节点为第一层
int leftLevel = (left == null?-1:left.level(object));
int rightLevel = (right == null?-1:right.level(object));
if(leftLevel0rightLevel0)
return -1;
levelInTree = leftLevelrightLevel?rightLevel:leftLevel;
return 1+levelInTree;
}
//将树中的每个节点的孩子对换位置
public void reflect()
{
if(this == null)
return;
if(left != null)
left.reflect();
if(right != null)
right.reflect();
BinTree temp = left;
left = right;
right = temp;
}// 将树中的所有节点移走,并输出移走的节点
public void defoliate()
{
String innerNode = "";
if(this == null)
return;
//若本节点是叶节点，则将其移走
if(left==nullright == null)
{
System.out.print(this + " ");
data = null;
return;
}
//移走左子树若其存在
if(left!=null){
left.defoliate();
left = null;
}
//移走本节点，放在中间表示中跟移走...
innerNode += this + " ";
data = null;
//移走右子树若其存在
if(right!=null){
right.defoliate();
right = null;
}
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
BinTree e = new BinTree("E");
BinTree g = new BinTree("G");
BinTree h = new BinTree("H");
BinTree i = new BinTree("I");
BinTree d = new BinTree("D",null,g);
BinTree f = new BinTree("F",h,i);
BinTree b = new BinTree("B",d,e);
BinTree c = new BinTree("C",f,null);
BinTree tree = new BinTree("A",b,c);
System.out.println("前序遍历二叉树结果: ");
tree.preOrder(tree);
System.out.println();
System.out.println("中序遍历二叉树结果: ");
tree.inOrder(tree);
System.out.println();
System.out.println("后序遍历二叉树结果: ");
tree.postOrder(tree);
System.out.println();
System.out.println("层次遍历二叉树结果: ");
tree.LayerOrder(tree);
System.out.println();
System.out.println("F所在的层次: "+tree.level("F"));
System.out.println("这棵二叉树的高度: "+tree.height());
System.out.println("--------------------------------------");
tree.reflect();
System.out.println("交换每个节点的孩子节点后......");
System.out.println("前序遍历二叉树结果: ");
tree.preOrder(tree);
System.out.println();
System.out.println("中序遍历二叉树结果: ");
tree.inOrder(tree);
System.out.println();
System.out.println("后序遍历二叉树结果: ");
tree.postOrder(tree);
System.out.println();
System.out.println("层次遍历二叉树结果: ");
tree.LayerOrder(tree);
System.out.println();
System.out.println("F所在的层次: "+tree.level("F"));
System.out.println("这棵二叉树的高度: "+tree.height());
}
二叉树
1
2 3
4 5 6 7
这个二叉树的深度是3，树的深度是最大结点所在的层，这里是3.
应该计算所有结点层数，选择最大的那个。
根据上面的二叉树代码，递归过程是：
f(1)=f(2)+1 f(3) +1 ? f(2) + 1 : f(3) +1
f(2) 跟f(3)计算类似上面，要计算左右结点，然后取大者
所以计算顺序是f(4.left) = 0, f(4.right) = 0
f(4) = f(4.right) + 1 = 1
然后计算f(5.left) = 0,f(5.right) = 0
f(5) = f(5.right) + 1 =1
f(2) = f(5) + 1 =2
f(1.left) 计算完毕，计算f(1.right) f(3) 跟计算f(2)的过程一样。
得到f(3) = f(7) +1 = 2
f(1) = f(3) + 1 =3
if(depleftdepright){
return depleft+1;
}else{
return depright+1;
}
只有left大于right的时候采取left +1，相等是取right
import java.util.ArrayList;
public class TreeNode {
private TreeNode leftNode;
private TreeNode rightNode;
private String nodeName;
public TreeNode getLeftNode() {
return leftNode;
}
public void setLeftNode(TreeNode leftNode) {
this.leftNode = leftNode;
}
public TreeNode getRightNode() {
return rightNode;
}
public void setRightNode(TreeNode rightNode) {
this.rightNode = rightNode;
}
public String getNodeName() {
return nodeName;
}
public void setNodeName(String nodeName) {
this.nodeName = nodeName;
}
public static int level=0;
public static void findNodeByLevel(ArrayListTreeNode nodes){
if(nodes==null||nodes.size()==0){
return ;
}
level++;
ArrayListTreeNode temp = new ArrayList();
for(TreeNode node:nodes){
System.out.println("第"+level+"层:"+node.getNodeName());
if(node.getLeftNode()!=null){
temp.add(node.getLeftNode());
}
if(node.getRightNode()!=null){
temp.add(node.getRightNode());
}
}
nodes.removeAll(nodes);
findNodeByLevel(temp);
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
TreeNode root = new TreeNode();
root.setNodeName("root");
TreeNode node1 = new TreeNode();
node1.setNodeName("node1");
TreeNode node3 = new TreeNode();
node3.setNodeName("node3");
TreeNode node7 = new TreeNode();
node7.setNodeName("node7");
TreeNode node8 = new TreeNode();
node8.setNodeName("node8");
TreeNode node4 = new TreeNode();
node4.setNodeName("node4");
TreeNode node2 = new TreeNode();
node2.setNodeName("node2");
TreeNode node5 = new TreeNode();
node5.setNodeName("node5");
TreeNode node6 = new TreeNode();
node6.setNodeName("node6");
root.setLeftNode(node1);
node1.setLeftNode(node3);
node3.setLeftNode(node7);
node3.setRightNode(node8);
node1.setRightNode(node4);
root.setRightNode(node2);
node2.setLeftNode(node5);
node2.setRightNode(node6);
ArrayListTreeNode nodes = new ArrayListTreeNode();
nodes.add(root);
findNodeByLevel(nodes);
}
}