从上到下按层打印二叉树，同一层的结点按从左到右的顺序打印，每一层打印一行。

最新推荐文章于 2022-06-20 10:34:55 发布

kallenhy

最新推荐文章于 2022-06-20 10:34:55 发布

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文章标签：算法二叉树数据结构

本文链接：https://blog.youkuaiyun.com/nijijiao8418/article/details/79141312

本文提供了一个使用Java实现的二叉树层次遍历的示例代码。通过队列来跟踪节点并按层级打印，展示了如何创建二叉树结构、填充节点以及进行层次遍历的过程。

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import java.util.LinkedList;


import java.util.Queue;
import java.util.ArrayList;
import java.util.Iterator;
public class BinaryTree_E2{
private static class BinaryTreeNode{
private int val;
private BinaryTreeNode left;
private BinaryTreeNode right;

public BinaryTreeNode() {

}

public BinaryTreeNode(int val) {
this.val = val;
}

public String toString() {
return val + "" ;
}
}

public static void printTree(BinaryTreeNode root) {

//ArrayList<Integer> list = new ArrayList<Integer>();
Queue<BinaryTreeNode> queue = new LinkedList<>();
BinaryTreeNode nlast = root;
BinaryTreeNode last = root;
if(null == root) {
return;
}

queue.offer(root);
while(!queue.isEmpty()) {
BinaryTreeNode node = queue.poll();
System.out.print(node.val);
System.out.print('\t');
if(node.left != null) {
queue.offer(node.left);
nlast = node.left;
}
if(node.right != null) {
queue.offer(node.right);
nlast = node.right;
}
if(node == last) {
System.out.println();
last = nlast;
}

}
}


public static void main(String[] args) {
BinaryTreeNode n1 = new BinaryTreeNode(1);
BinaryTreeNode n2 = new BinaryTreeNode(2);
BinaryTreeNode n3 = new BinaryTreeNode(3);
BinaryTreeNode n4 = new BinaryTreeNode(4);
BinaryTreeNode n5 = new BinaryTreeNode(5);
BinaryTreeNode n6 = new BinaryTreeNode(6);
BinaryTreeNode n7 = new BinaryTreeNode(7);
BinaryTreeNode n8 = new BinaryTreeNode(8);
BinaryTreeNode n9 = new BinaryTreeNode(9);

n1.left = n2;
n1.right = n3;
n2.left = n4;
n2.right = n5;
n3.left = n6;
n3.right = n7;
n6.left = n8;
n6.right = n9;

printTree(n1);
}
}