929. Unique Email Addresses

arai60/unique-email-addresses/README.md

@@ -0,0 +1,40 @@
+## 考察
+- 初見の問題
+- 方針
+    - 文字列操作してHashSetに追加すればよさそう
+        - C++にはたしかsplitがなかったはずなので、Pythonでやる
+        - 文字列操作の代わりに正規表現でも出来そう
+            - ソラでは書ける自信がない(書けるようになっておいた方がいい？)
+            - 後ほど、調べながらやる
+        - time: O(nm), space: O(nm)
+        - n: emails.length, m: max_i(emails[i].length)
+- あとは実装
+
+## Step1
+- splitとreplaceを使った
+- time: O(nm), space: O(nm)
+
+## Step2
+- まずは正規表現でもやってみる -> `step2_re.py`
+- 他の人のPRを検索
+    - splitしてからreplaceした方が効率が良い
+        - Ref. https://github.com/Mike0121/LeetCode/pull/31#discussion_r1642845600
+    - 各emailに対する処理は関数化した方がわかりやすいかも
+        - Ref. https://github.com/SuperHotDogCat/coding-interview/pull/30/files#r1641769186
+    - 正規表現について
+        - Ref. https://github.com/fhiyo/leetcode/pull/17#discussion_r1629618002
+
+- 上記を元に各操作を関数化して組み合わせる書き方に修正した
+- local_nameとdomain_nameの組み合わせをtupleで表現した
+
+## Step3
+- 1回目: 2m19s
+- 2回目: 2m15s
+- 3回目: 2m02s
+
+## Step4
+- レビューを元に修正
+- privateメソッド相当のものには先頭に _ を付与
+- メソッド名の見直し
+    - `claen_local_name` -> `_normalize_local_name`
+    - `remove_after_plus` -> `_remove_plus_and_after`

arai60/unique-email-addresses/step1.py

@@ -0,0 +1,9 @@
+class Solution:
+    def numUniqueEmails(self, emails: List[str]) -> int:
+        unique_emails = set()
+        for email in emails:
+            local_name, domain_name = email.split('@')
+            formatted_local_name = local_name.replace('.', '').split('+')[0]
+            unique_emails.add(formatted_local_name + '@' + domain_name)
+
+        return len(unique_emails)

arai60/unique-email-addresses/step2.py

@@ -0,0 +1,20 @@
+class Solution:
+    def numUniqueEmails(self, emails: List[str]) -> int:
+        unique_emails = set()
+        for email in emails:
+            local_name, domain_name = email.split('@')
+            unique_emails.add((
+                self.clean_local_name(local_name),
+                domain_name,
+            ))
+
+        return len(unique_emails)
+
+    def clean_local_name(self, local_name):
+        return self.remove_all_dots(self.remove_after_plus(local_name))
+
+    def remove_all_dots(self, text):
+        return text.replace('.', '')
+
+    def remove_after_plus(self, text):
+        return text.split('+')[0]

arai60/unique-email-addresses/step2_re.py

@@ -0,0 +1,10 @@
+class Solution:
+    def numUniqueEmails(self, emails: List[str]) -> int:
+        unique_emails = set()
+        for email in emails:
+            local_name, domain_name = email.split('@')
+            local_name = re.sub(r'\+.*', '', local_name)
+            local_name = re.sub(r'\.', '', local_name)
+            unique_emails.add(local_name + '@' + domain_name)
+
+        return len(unique_emails)

arai60/unique-email-addresses/step3.py

@@ -0,0 +1,19 @@
+class Solution:
+    def numUniqueEmails(self, emails: List[str]) -> int:
+        unique_emails = set()
+        for email in emails:
+            local_name, domain_name = email.split('@')
+            unique_emails.add((
+                self.clean_local_name(local_name),
+                domain_name,
+            ))
+        return len(unique_emails)
+
+    def clean_local_name(self, local_name):
+        return self.remove_all_dots(self.remove_after_plus(local_name))
+
+    def remove_all_dots(self, text):
+        return text.replace('.', '')
+
+    def remove_after_plus(self, text):
+        return text.split('+')[0]

arai60/unique-email-addresses/step4.py

@@ -0,0 +1,19 @@
+class Solution:
+    def numUniqueEmails(self, emails: List[str]) -> int:
+        unique_emails = set()
+        for email in emails:
+            local_name, domain_name = email.split('@')
+            unique_emails.add((
+                self._normalize_local_name(local_name),
+                domain_name,
+            ))
+        return len(unique_emails)
+
+    def _normalize_local_name(self, local_name):
+        return self._remove_all_dots(self._remove_plus_and_after(local_name))
+
+    def _remove_all_dots(self, text):
+        return text.replace('.', '')
+
+    def _remove_plus_and_after(self, text):
+        return text.split('+')[0]