Add kotlin code for the chapter of tree (#1172)

* modified array.kt. * feat(kotlin): add kotlin code for the chapter of stack and queue. * modified array.kt * modified comments. * feat(kotlin): add kotlin code for the chapter of tree. * feat(kotlin): add kotlin code for the chapter of tree.
2026-07-15 08:26:06 +00:00 · 2024-03-25 16:22:17 +08:00
parent 202450420d
commit 5e77a64341
6 changed files with 613 additions and 0 deletions
@@ -0,0 +1,41 @@
+/**
+ * File: binary_tree_bfs.kt
+ * Created Time: 2024-01-25
+ * Author: curtishd (1023632660@qq.com)
+ */
+
+package chapter_tree
+
+import utils.TreeNode
+import utils.printTree
+import java.util.*
+
+/* 层序遍历 */
+fun levelOrder(root: TreeNode?): MutableList<Int> {
+    // 初始化队列，加入根节点
+    val queue = LinkedList<TreeNode?>()
+    queue.add(root)
+    // 初始化一个列表，用于保存遍历序列
+    val list = ArrayList<Int>()
+    while (!queue.isEmpty()) {
+        val node = queue.poll() // 队列出队
+        list.add(node?.value!!) // 保存节点值
+        if (node.left != null) queue.offer(node.left) // 左子节点入队
+
+        if (node.right != null) queue.offer(node.right) // 右子节点入队
+    }
+    return list
+}
+
+/* Driver Code */
+fun main() {
+    /* 初始化二叉树 */
+    // 这里借助了一个从数组直接生成二叉树的函数
+    val root = TreeNode.listToTree(mutableListOf(1, 2, 3, 4, 5, 6, 7))
+    println("\n初始化二叉树\n")
+    printTree(root)
+
+    /* 层序遍历 */
+    val list = levelOrder(root)
+    println("\n层序遍历的节点打印序列 = $list")
+}