From 09f9b834e19879a496d102db557847ca5e6e59a8 Mon Sep 17 00:00:00 2001
From: mike <59136831+Mike0121@users.noreply.github.com>
Date: Thu, 2 May 2024 19:28:23 +0900
Subject: [PATCH 1/2] 102. Binary Tree Level Order Traversal.md

https://leetcode.com/problems/binary-tree-level-order-traversal/description/
---
 ...102. Binary Tree Level Order Traversal.md" | 88 +++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 "\347\253\266\346\212\200\343\203\227\343\203\255\345\260\261\346\264\273\351\203\250PR\347\224\250/102. Binary Tree Level Order Traversal.md"

diff --git "a/\347\253\266\346\212\200\343\203\227\343\203\255\345\260\261\346\264\273\351\203\250PR\347\224\250/102. Binary Tree Level Order Traversal.md" "b/\347\253\266\346\212\200\343\203\227\343\203\255\345\260\261\346\264\273\351\203\250PR\347\224\250/102. Binary Tree Level Order Traversal.md"
new file mode 100644
index 0000000..189cce1
--- /dev/null
+++ "b/\347\253\266\346\212\200\343\203\227\343\203\255\345\260\261\346\264\273\351\203\250PR\347\224\250/102. Binary Tree Level Order Traversal.md"	
@@ -0,0 +1,88 @@
+15分で1回目は解けず、どのようにして同じ階層のノードを取り出して処理し、次の階層に移動するかが整理できませんでした。
+各階層から値を列挙した後に、その回数分for文を回すのは、BFSの基本ができていないから思いつかなかった(考えられなかった)のかなと思います。
+
+### 1回目
+時間計算量: O(N)
+空間計算量: O(N + 正解分)
+```python
+class Solution:
+    def levelOrder(self, root: Optional[TreeNode]) -> List[List[int]]:
+        if not root:
+            return []
+
+        result = []
+        next_level_nodes = deque()
+        next_level_nodes.append(root)
+
+        while next_level_nodes:
+            same_level_nodes = []
+            for i in range(len(next_level_nodes)):
+                node = next_level_nodes.popleft()
+                same_level_nodes.append(node.val)
+
+                if node.left:
+                    next_level_nodes.append(node.left)
+                    
+                if node.right:
+                    next_level_nodes.append(node.right)
+                    
+            result.append(same_level_nodes)
+
+        return result
+```
+
+
+理屈が頭の中にある程度整理されていれば、余計な改行が減る気がしました。
+
+ ### 2回目
+ ```python
+ class Solution:
+    def levelOrder(self, root: Optional[TreeNode]) -> List[List[int]]:
+        if not root:
+            return []
+        
+        result = []
+        next_level_nodes = deque()
+        next_level_nodes.append(root)
+
+        while next_level_nodes:
+            same_level_nodes = []
+            for _ in range(len(next_level_nodes)):
+                node = next_level_nodes.popleft()
+                same_level_nodes.append(node.val)
+                if node.left:
+                    next_level_nodes.append(node.left)
+                if node.right:
+                    next_level_nodes.append(node.right)
+
+            result.append(same_level_nodes)
+        return result
+```
+
+next_level_nodes, same_level_valuesは、next_level, same_levelでも良いかと思った。
+
+ ### 3回目
+ ```python
+class Solution:
+    def levelOrder(self, root: Optional[TreeNode]) -> List[List[int]]:
+        if not root:
+            return []
+        
+        result = []
+        next_level_nodes = deque()
+        next_level_nodes.append(root)
+
+        while next_level_nodes:
+            same_level_values = []
+            
+            for _ in range(len(next_level_nodes)):
+                node = next_level_nodes.popleft()
+                same_level_values.append(node.val)
+                if node.left:
+                    next_level_nodes.append(node.left)
+                if node.right:
+                    next_level_nodes.append(node.right)
+            result.append(same_level_values)
+        
+        return result
+ ```

From 7b5b2b7dfd5d3ea3fa6e57dc50527169c860cb39 Mon Sep 17 00:00:00 2001
From: mike <59136831+Mike0121@users.noreply.github.com>
Date: Thu, 2 May 2024 20:30:36 +0900
Subject: [PATCH 2/2] Update 102. Binary Tree Level Order Traversal.md
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

listによる解法を追加
---
 ...102. Binary Tree Level Order Traversal.md" | 28 +++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git "a/\347\253\266\346\212\200\343\203\227\343\203\255\345\260\261\346\264\273\351\203\250PR\347\224\250/102. Binary Tree Level Order Traversal.md" "b/\347\253\266\346\212\200\343\203\227\343\203\255\345\260\261\346\264\273\351\203\250PR\347\224\250/102. Binary Tree Level Order Traversal.md"
index 189cce1..c37f32b 100644
--- "a/\347\253\266\346\212\200\343\203\227\343\203\255\345\260\261\346\264\273\351\203\250PR\347\224\250/102. Binary Tree Level Order Traversal.md"	
+++ "b/\347\253\266\346\212\200\343\203\227\343\203\255\345\260\261\346\264\273\351\203\250PR\347\224\250/102. Binary Tree Level Order Traversal.md"	
@@ -86,3 +86,31 @@ class Solution:
         
         return result
  ```
+
+
+### 4回目 (listによる解答)
+```python
+class Solution:
+    def levelOrder(self, root: Optional[TreeNode]) -> List[List[int]]:
+        if not root:
+            return []
+        
+        level_ordered_values = []
+        current_level_nodes = [root]
+
+        while current_level_nodes:
+            same_level_values = []
+            next_level_nodes = []
+            
+            for i in range(len(current_level_nodes)):
+                node = current_level_nodes[i]
+                same_level_values.append(node.val)
+                if node.left:
+                    next_level_nodes.append(node.left)
+                if node.right:
+                    next_level_nodes.append(node.right)
+            current_level_nodes = next_level_nodes
+            level_ordered_values.append(same_level_values)
+        
+        return level_ordered_values
+```