Merge branch 'master' of github.com:youngyangyang04/leetcode-master

problems/0102.二叉树的层序遍历.md

@@ -271,6 +271,36 @@ func levelOrder(root *TreeNode) [][]int {
     
     return res
 }
+
+/**
+102. 二叉树的层序遍历：使用切片模拟队列，易理解
+ */
+func levelOrder(root *TreeNode) (res [][]int) {
+    if root == nil {
+        return 
+    }
+
+    curLevel := []*TreeNode{root}  // 存放当前层节点
+    for len(curLevel) > 0 {
+        nextLevel := []*TreeNode{}  // 准备通过当前层生成下一层
+        vals := []int{}
+
+        for _, node := range curLevel {
+            vals = append(vals, node.Val) // 收集当前层的值
+            // 收集下一层的节点
+            if node.Left != nil {
+                nextLevel = append(nextLevel, node.Left)
+            }
+            if node.Right != nil {
+                nextLevel = append(nextLevel, node.Right)
+            }
+        }
+        res = append(res, vals)
+        curLevel = nextLevel // 将下一层变成当前层
+    }
+
+    return
+}
 ```
 
 javascript代码：
@@ -1072,7 +1102,6 @@ public class N0637 {
 
         que.offerLast(root);
         while (!que.isEmpty()) {
-            TreeNode peek = que.peekFirst();
 
             int levelSize = que.size();
             double levelSum = 0.0;
@@ -1346,6 +1375,22 @@ class Solution:
         return results
 ```
 
+```python
+# LeetCode 429. N-ary Tree Level Order Traversal
+# 递归法
+class Solution:
+    def levelOrder(self, root: 'Node') -> List[List[int]]:
+        if not root: return []
+        result=[]
+        def traversal(root,depth):
+            if len(result)==depth:result.append([])
+            result[depth].append(root.val)
+            if root.children: 
+                for i in range(len(root.children)):traversal(root.children[i],depth+1)
+            
+        traversal(root,0)
+        return result        
+```
 java:
 
 ```java 
@@ -2955,7 +3000,7 @@ impl Solution {
 * 107.二叉树的层次遍历II
 * 199.二叉树的右视图
 * 637.二叉树的层平均值
-* 429.N叉树的前序遍历
+* 429.N叉树的层序遍历
 * 515.在每个树行中找最大值
 * 116.填充每个节点的下一个右侧节点指针
 * 117.填充每个节点的下一个右侧节点指针II
@@ -2970,3 +3015,4 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+