Add solution 0429

leetcode/0429.N-ary-Tree-Level-Order-Traversal/429. N-ary Tree Level Order Traversal.go

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+package leetcode
+
+/**
+ * Definition for a Node.
+ * type Node struct {
+ *     Val int
+ *     Children []*Node
+ * }
+ */
+
+type Node struct {
+	Val      int
+	Children []*Node
+}
+
+func levelOrder(root *Node) [][]int {
+	var res [][]int
+	var temp []int
+	if root == nil {
+		return res
+	}
+	queue := []*Node{root, nil}
+	for len(queue) > 1 {
+		node := queue[0]
+		queue = queue[1:]
+		if node == nil {
+			queue = append(queue, nil)
+			res = append(res, temp)
+			temp = []int{}
+		} else {
+			temp = append(temp, node.Val)
+			if len(node.Children) > 0 {
+				queue = append(queue, node.Children...)
+			}
+		}
+	}
+	res = append(res, temp)
+	return res
+}

leetcode/0429.N-ary-Tree-Level-Order-Traversal/README.md

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+# [429. N-ary Tree Level Order Traversal](https://leetcode.com/problems/n-ary-tree-level-order-traversal/)
+
+
+## 题目
+
+Given an n-ary tree, return the *level order* traversal of its nodes' values.
+
+*Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples).*
+
+**Example 1:**
+
+![https://assets.leetcode.com/uploads/2018/10/12/narytreeexample.png](https://assets.leetcode.com/uploads/2018/10/12/narytreeexample.png)
+
+```
+Input: root = [1,null,3,2,4,null,5,6]
+Output: [[1],[3,2,4],[5,6]]
+
+```
+
+**Example 2:**
+
+![https://assets.leetcode.com/uploads/2019/11/08/sample_4_964.png](https://assets.leetcode.com/uploads/2019/11/08/sample_4_964.png)
+
+```
+Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
+Output: [[1],[2,3,4,5],[6,7,8,9,10],[11,12,13],[14]]
+
+```
+
+**Constraints:**
+
+- The height of the n-ary tree is less than or equal to `1000`
+- The total number of nodes is between `[0, 104]`
+
+## 题目大意
+
+给定一个 N 叉树，返回其节点值的层序遍历。（即从左到右，逐层遍历）。树的序列化输入是用层序遍历，每组子节点都由 null 值分隔（参见示例）。
+
+## 解题思路
+
+- 这是 n 叉树的系列题，第 589 题也是这一系列的题目。这一题思路不难，既然是层序遍历，用 BFS 解答。
+
+## 代码
+
+```go
+package leetcode
+
+/**
+ * Definition for a Node.
+ * type Node struct {
+ *     Val int
+ *     Children []*Node
+ * }
+ */
+
+type Node struct {
+	Val      int
+	Children []*Node
+}
+
+func levelOrder(root *Node) [][]int {
+	var res [][]int
+	var temp []int
+	if root == nil {
+		return res
+	}
+	queue := []*Node{root, nil}
+	for len(queue) > 1 {
+		node := queue[0]
+		queue = queue[1:]
+		if node == nil {
+			queue = append(queue, nil)
+			res = append(res, temp)
+			temp = []int{}
+		} else {
+			temp = append(temp, node.Val)
+			if len(node.Children) > 0 {
+				queue = append(queue, node.Children...)
+			}
+		}
+	}
+	res = append(res, temp)
+	return res
+}
+```