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BinaryTree.java
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104 lines (96 loc) · 3.07 KB
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import java.util.ArrayDeque;
public class BinaryTree {
static class TreeNode{
int value;
TreeNode left;
TreeNode right;
public TreeNode(int value){
this.value=value;
}
}
TreeNode root;
public BinaryTree(int[] array){
root=makeBinaryTreeByArray(array,1);
}
/**
* 采用递归的方式创建一颗二叉树
* 传入的是二叉树的数组表示法
* 构造后是二叉树的二叉链表表示法
*/
public static TreeNode makeBinaryTreeByArray(int[] array,int index){
if(index<array.length){
int value=array[index];
if(value!=0){
TreeNode t=new TreeNode(value);
array[index]=0;
t.left=makeBinaryTreeByArray(array,index*2);
t.right=makeBinaryTreeByArray(array,index*2+1);
return t;
}
}
return null;
}
/**
* 深度优先遍历，相当于先根遍历
* 采用非递归实现
* 需要辅助数据结构：栈
*/
public void depthOrderTraversal(){
if(root==null){
System.out.println("empty tree");
return;
}
ArrayDeque<TreeNode> stack=new ArrayDeque<TreeNode>();
stack.push(root);
while(stack.isEmpty()==false){
TreeNode node=stack.pop();
System.out.print(node.value+" ");
if(node.right!=null){
stack.push(node.right);
}
if(node.left!=null){
stack.push(node.left);
}
}
System.out.print("\n");
}
/**
* 广度优先遍历
* 采用非递归实现
* 需要辅助数据结构：队列
*/
public void levelOrderTraversal(){
if(root==null){
System.out.println("empty tree");
return;
}
ArrayDeque<TreeNode> queue=new ArrayDeque<TreeNode>();
queue.add(root);
while(queue.isEmpty()==false){
TreeNode node=queue.remove();
System.out.print(node.value+" ");
if(node.left!=null){
queue.add(node.left);
}
if(node.right!=null){
queue.add(node.right);
}
}
System.out.print("\n");
}
/**
* 13
* / \
* 65 5
* / \ \
* 97 25 37
* / /\ /
* 22 4 28 32
*/
public static void main(String[] args) {
int[] arr={0,13,65,5,97,25,0,37,22,0,4,28,0,0,32,0};
BinaryTree tree=new BinaryTree(arr);
tree.depthOrderTraversal();
tree.levelOrderTraversal();
}
}