From dc9d19a8b17460f7ad03205be1f6b202fa458a39 Mon Sep 17 00:00:00 2001
From: aiueoriku <112373068+aiueoriku@users.noreply.github.com>
Date: Fri, 23 May 2025 14:24:34 +0900
Subject: [PATCH 1/2] Create First Unique Character in a String.md

problem:
https://leetcode.com/problems/first-unique-character-in-a-string/description/
---
 .../First Unique Character in a String.md     | 44 +++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 First Unique Character in a String/First Unique Character in a String.md

diff --git a/First Unique Character in a String/First Unique Character in a String.md b/First Unique Character in a String/First Unique Character in a String.md
new file mode 100644
index 0000000..32845c7
--- /dev/null
+++ b/First Unique Character in a String/First Unique Character in a String.md	
@@ -0,0 +1,44 @@
+# Step1
+何も見ずに解く
+```python
+class Solution:
+    def firstUniqChar(self, s: str) -> int:
+        for i, char in enumerate(s):
+            if char not in s[i+1:] and char not in s[:i]:
+                return i
+        return -1
+
+```
+for文で虱潰しに調べた．もっと良いアルゴリズムが有りそう．
+
+# Step2
+他の人の解答を参照
+https://github.com/rinost081/LeetCode/pull/14
+https://github.com/Satorien/LeetCode/pull/15/
+
+- Counterメソッドを使うと文字の出現回数を辞書のように保持できて便利
+- Counterメソッドを持ちいらずに辞書を自分で定義して出現回数を保持するということも出来る
+
+# Step3
+他の人の解答を参考に解き直す
+```python
+class Solution:
+    def firstUniqChar(self, s: str) -> int:
+        char_to_count = Counter(s)
+        for i, char in enumerate(s):
+            if char_to_count[char] == 1:
+                return i
+        return -1
+```
+```python
+class Solution:
+    def firstUniqChar(self, s: str) -> int:
+        char_to_count = defaultdict(int)
+        for char in s:
+            char_to_count[char] += 1
+        for i, char in enumerate(s):
+            if char_to_count[char]==1:
+                return i
+        return -1
+```
+Counterを使うほうが簡潔だし，処理速度も早い．

From d21b24a434ee7b2b11288453ef309981a7b04d5e Mon Sep 17 00:00:00 2001
From: aiueoriku <112373068+aiueoriku@users.noreply.github.com>
Date: Mon, 26 May 2025 13:24:45 +0900
Subject: [PATCH 2/2] add Step4

---
 .../First Unique Character in a String.md     | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/First Unique Character in a String/First Unique Character in a String.md b/First Unique Character in a String/First Unique Character in a String.md
index 32845c7..d04a883 100644
--- a/First Unique Character in a String/First Unique Character in a String.md	
+++ b/First Unique Character in a String/First Unique Character in a String.md	
@@ -42,3 +42,24 @@ class Solution:
         return -1
 ```
 Counterを使うほうが簡潔だし，処理速度も早い．
+
+# Step4
+コメントを受けて再度解き直す
+```python
+class Solution:
+    def firstUniqChar(self, s: str) -> int:
+        char_to_count = defaultdict(int)
+        char_to_index = {}
+        for index, char in enumerate(s):
+            char_to_count[char] += 1
+            if char not in char_to_index:
+                char_to_index[char] = index
+        
+        min_index = len(s)
+        for char, count in char_to_count.items():
+            if count == 1:
+                if char_to_index[char] < min_index:
+                    min_index = char_to_index[char]
+        return min_index if min_index != len(s) else -1
+```
+char_to_indexに各文字の最初のインデックスを保持して，文字列全体に対するfor文の回数を1回で済むように改変した．