From 2b28aeeac54cd01e06447b077faa35cfba7cc890 Mon Sep 17 00:00:00 2001
From: aiueoriku <112373068+aiueoriku@users.noreply.github.com>
Date: Wed, 21 May 2025 10:50:55 +0900
Subject: [PATCH 1/3] Create GroupAnagrams.md

Problem:
https://leetcode.com/problems/group-anagrams/description/
---
 GroupAnagrams/GroupAnagrams.md | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 GroupAnagrams/GroupAnagrams.md

diff --git a/GroupAnagrams/GroupAnagrams.md b/GroupAnagrams/GroupAnagrams.md
new file mode 100644
index 0000000..c72cde8
--- /dev/null
+++ b/GroupAnagrams/GroupAnagrams.md
@@ -0,0 +1,33 @@
+# Step1
+何も見ずに解く
+```python
+class Solution:
+    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
+        anagrams = []
+        str_dict = {}
+        for str in strs:
+            str_dict[str] = sorted(str)
+        print(str_dict)
+```
+出力
+```
+{'eat': ['a', 'e', 't'], 'tea': ['a', 'e', 't'], 'tan': ['a', 'n', 't'], 'ate': ['a', 'e', 't'], 'nat': ['a', 'n', 't'], 'bat': ['a', 'b', 't']}
+```
+辞書のバリューから逆引きしたかったが，文法がわからず断念．
+ChatGPTに聞いた結果，str_dict.items()でキーとバリューが取得できる．
+listはハッシュに使えないので，予め文字列に変換したほうが良さそう．
+また，defaultdictという方法が有効だと感じたのでそれを使うことにする．
+
+
+# Step2
+調べた結果を受けてときなおし
+```python
+class Solution:
+    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
+        anagrams = defaultdict(list)
+        for str in strs:
+            str_sorted = ''.join(sorted(str))
+            anagrams[str_sorted].append(str)
+        return list(anagrams.values())
+```
+defaultdictという文法を使うことで簡潔にかけたが，初期の方針でも書けるようにしたほうが良い気がする．

From 310032dfdbfb2659d9b6e029c1162a67fab77816 Mon Sep 17 00:00:00 2001
From: aiueoriku <112373068+aiueoriku@users.noreply.github.com>
Date: Wed, 21 May 2025 11:13:29 +0900
Subject: [PATCH 2/3] withought defaultstatedict

---
 GroupAnagrams/GroupAnagrams.md | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/GroupAnagrams/GroupAnagrams.md b/GroupAnagrams/GroupAnagrams.md
index c72cde8..ca5e3bd 100644
--- a/GroupAnagrams/GroupAnagrams.md
+++ b/GroupAnagrams/GroupAnagrams.md
@@ -31,3 +31,25 @@ class Solution:
         return list(anagrams.values())
 ```
 defaultdictという文法を使うことで簡潔にかけたが，初期の方針でも書けるようにしたほうが良い気がする．
+
+# Step3
+初期の方針，つまりdefauldictを用いらずに解く
+```python
+class Solution:
+    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
+        anagrams = {}
+
+        for str in strs:
+            str_sorted = "".join(sorted(str))
+            anagrams[str] = str_sorted
+
+        anagram_groups = {}
+        for str, str_sorted in anagrams.items():
+            if str_sorted not in anagram_groups:
+                anagram_groups[str_sorted] = []
+            anagram_groups[str_sorted].append(str)
+            
+        return [x for x in anagram_groups.values()]
+```
+strs = ["",""]に対して，出力がstrs =
+[""]となりエラー．

From 65378124133f8c92b76e7d4e84fb3a1495b02591 Mon Sep 17 00:00:00 2001
From: aiueoriku <112373068+aiueoriku@users.noreply.github.com>
Date: Thu, 22 May 2025 09:48:33 +0900
Subject: [PATCH 3/3] add Step4
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

コメントを元に修正
---
 GroupAnagrams/GroupAnagrams.md | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/GroupAnagrams/GroupAnagrams.md b/GroupAnagrams/GroupAnagrams.md
index ca5e3bd..70bad13 100644
--- a/GroupAnagrams/GroupAnagrams.md
+++ b/GroupAnagrams/GroupAnagrams.md
@@ -53,3 +53,18 @@ class Solution:
 ```
 strs = ["",""]に対して，出力がstrs =
 [""]となりエラー．
+
+# Step4
+コメントを元に解き直し
+```python
+class Solution:
+    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
+        str_to_sorted = {}
+        for s in strs:
+            s_sorted = "".join(sorted(s))
+            if s_sorted not in str_to_sorted:
+                str_to_sorted[s_sorted] = []
+            str_to_sorted[s_sorted].append(s)
+        return [word for word in str_to_sorted.values()]
+```
+Step3でおきたエラーも消えた．