From f6be8e3126f562282f51cba4aee4d4759ae01e74 Mon Sep 17 00:00:00 2001
From: Hiro Funatsuka <hiro.funatsuka@gmail.com>
Date: Thu, 21 May 2026 23:21:08 +0900
Subject: [PATCH 1/2] Solve group anagrams

---
 49_group_anagrams/problem.md |  1 +
 49_group_anagrams/step1.md   | 22 ++++++++++++++++++++++
 49_group_anagrams/step2.md   | 20 ++++++++++++++++++++
 49_group_anagrams/step3.md   | 20 ++++++++++++++++++++
 4 files changed, 63 insertions(+)
 create mode 100644 49_group_anagrams/problem.md
 create mode 100644 49_group_anagrams/step1.md
 create mode 100644 49_group_anagrams/step2.md
 create mode 100644 49_group_anagrams/step3.md

diff --git a/49_group_anagrams/problem.md b/49_group_anagrams/problem.md
new file mode 100644
index 0000000..e7dac33
--- /dev/null
+++ b/49_group_anagrams/problem.md
@@ -0,0 +1 @@
+## 問題: [560. Group Anagrams](https://leetcode.com/problems/group-anagrams/description/)
diff --git a/49_group_anagrams/step1.md b/49_group_anagrams/step1.md
new file mode 100644
index 0000000..4cacaf9
--- /dev/null
+++ b/49_group_anagrams/step1.md
@@ -0,0 +1,22 @@
+# Step 1
+
+- string毎に、アルファベットが何回出たかをa-zの配列に記録する
+- dictに配列をキーとする、stringを追加していく
+
+```python
+class Solution:
+    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
+        unordered_characters_to_words = defaultdict(list)
+        for word in strs:
+            key = [0] * 26
+            for character in word:
+                key[ord(character) - ord("a")] += 1
+            unordered_characters_to_words[tuple(key)].append(word)
+        return list(unordered_characters_to_words.values())
+```
+
+時間計算量: $O(mn)$
+
+空間計算量: $O(mn)$
+
+アルゴリズム最大実行時間(概算): 時間計算量 / Pythonの1秒あたりの計算ステップ数 -> $(10^4 \times 100) \div 10,000,000 = 0.1 (s)$
diff --git a/49_group_anagrams/step2.md b/49_group_anagrams/step2.md
new file mode 100644
index 0000000..d3bab23
--- /dev/null
+++ b/49_group_anagrams/step2.md
@@ -0,0 +1,20 @@
+# Step 2
+
+```python
+class Solution:
+    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
+        signature_to_words = defaultdict(list)
+        for word in strs:
+            key = [0] * 26
+            for character in word:
+                key[ord(character) - ord("a")] += 1
+            signature_to_words[tuple(key)].append(word)
+        return list(signature_to_words.values())
+
+```
+
+時間計算量: $O(mn)$
+
+空間計算量: $O(mn)$
+
+アルゴリズム最大実行時間(概算): 時間計算量 / Pythonの1秒あたりの計算ステップ数 -> $(10^4 \times 100) \div 10,000,000 = 0.1 (s)$
diff --git a/49_group_anagrams/step3.md b/49_group_anagrams/step3.md
new file mode 100644
index 0000000..d7087d2
--- /dev/null
+++ b/49_group_anagrams/step3.md
@@ -0,0 +1,20 @@
+# Step 3
+
+```python
+class Solution:
+    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
+        signature_to_words = defaultdict(list)
+        for word in strs:
+            key = [0] * 26
+            for character in word:
+                key[ord(character) - ord("a")] += 1
+            signature_to_words[tuple(key)].append(word)
+        return list(signature_to_words.values())
+
+```
+
+1回目: 1分　47秒
+
+2回目: 1分　28秒
+
+3回目: 1分　29秒

From aca67df42c582838b5fbc1b2b9a9ecfa4cf40875 Mon Sep 17 00:00:00 2001
From: Hiro Funatsuka <hiro.funatsuka@gmail.com>
Date: Thu, 21 May 2026 23:26:44 +0900
Subject: [PATCH 2/2] Correct the problem number

---
 49_group_anagrams/problem.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/49_group_anagrams/problem.md b/49_group_anagrams/problem.md
index e7dac33..60fecbf 100644
--- a/49_group_anagrams/problem.md
+++ b/49_group_anagrams/problem.md
@@ -1 +1 @@
-## 問題: [560. Group Anagrams](https://leetcode.com/problems/group-anagrams/description/)
+## 問題: [49. Group Anagrams](https://leetcode.com/problems/group-anagrams/description/)