37 lines
1.3 KiB
Java
37 lines
1.3 KiB
Java
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package chapter_tree;
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import include.*;
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import java.util.*;
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public class binary_tree_bfs {
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/* 层序遍历 */
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static List<Integer> hierOrder(TreeNode root) {
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// 初始化队列，加入根结点
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Queue<TreeNode> queue = new LinkedList<>() {{ add(root); }};
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// 初始化一个列表，用于保存遍历序列
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List<Integer> list = new ArrayList<>();
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while (!queue.isEmpty()) {
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TreeNode node = queue.poll(); // 队列出队
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list.add(node.val); // 保存结点
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if (node.left != null)
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queue.offer(node.left); // 左子结点入队
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if (node.right != null)
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queue.offer(node.right); // 右子结点入队
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}
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return list;
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}
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public static void main(String[] args) {
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/* 初始化二叉树 */
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// 这里借助了一个从数组直接生成二叉树的函数
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TreeNode root = TreeNode.arrToTree(new Integer[] {
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1, 2, 3, 4, 5, 6, 7, null, null, null, null, null, null, null, null });
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System.out.println("\n初始化二叉树\n");
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PrintUtil.printTree(root);
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/* 层序遍历 */
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List<Integer> list = hierOrder(root);
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System.out.println("\n层序遍历的结点打印序列 = " + list);
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}
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}
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