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myoshi2891 merged 1 commit into from
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feat: add solution and documentation for LeetCode 66. Plus One #241

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343 changes: 343 additions & 0 deletions Algorithm/Other/leetcode/66. Plus One/Claude Sonnet 4.5/PlusOne_python.ipynb
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{
"cells": [
{
"cell_type": "markdown",
"id": "464fa3b5",
"metadata": {},
"source": [
"# Python コーディング問題: Plus One\n",
"\n",
"## 1. 問題分析結果\n",
"\n",
"### 競技プログラミング視点\n",
"\n",
"- **制約分析**: \n",
" - 配列長: 1 ≤ len(digits) ≤ 100 → O(n)アルゴリズムで十分\n",
" - 各要素: 0 ≤ digits[i] ≤ 9 → 整数演算のみで処理可能\n",
" - 先頭に0なし → エッジケース考慮が簡素化\n",
" \n",
"- **最速手法**: \n",
" - 右から左への単一ループ（O(n)）\n",
" - 早期リターンで平均O(1)～O(n)\n",
" - in-place変更で追加メモリ最小化\n",
" \n",
"- **メモリ最小化**: \n",
" - 基本的にin-place操作でO(1)\n",
" - 全桁9のケースのみO(n)の新規メモリ\n",
" \n",
"- **CPython最適化**: \n",
" - リスト操作は全てC実装で高速\n",
" - `range()`の逆順イテレーションは効率的\n",
" - リスト結合は`[1] + digits`より`[1, *digits]`が推奨\n",
"\n",
"### 業務開発視点\n",
"\n",
"- **型安全設計**: \n",
" - `List[int]`での厳密な型ヒント\n",
" - pylance完全対応の型アノテーション\n",
" - Optional型での明示的なNone処理\n",
" \n",
"- **エラーハンドリング**: \n",
" - 入力検証（空配列、型チェック、範囲チェック）\n",
" - ValueError/TypeErrorの適切な使い分け\n",
" - docstringでの例外明記\n",
" \n",
"- **可読性**: \n",
" - 筆算アルゴリズムの直感的な実装\n",
" - 変数名の明確化（carry, digit等）\n",
" - 適切なコメント配置\n",
"\n",
"### Python特有分析\n",
"\n",
"- **データ構造選択**: \n",
" - リスト操作が中心 → `list`が最適\n",
" - 両端操作は少ない → `deque`不要\n",
" - 順序保持必須 → `set`は不適\n",
" \n",
"- **標準ライブラリ活用度**: \n",
" - この問題では標準ライブラリ不要（シンプルなリスト操作のみ）\n",
" - `collections`、`itertools`等は過剰\n",
" \n",
"- **CPython最適化度**: \n",
" - リスト走査は組み込みイテレータで高速\n",
" - リスト結合はスライシングよりスプレッド演算子\n",
" - インデックスアクセスはC実装で高速\n",
"\n",
"## 2. アルゴリズム比較表\n",
"\n",
"|アプローチ|時間計算量|空間計算量|Python実装コスト|可読性|標準ライブラリ活用|CPython最適化|備考|\n",
"|---------|---------|---------|---------------|------|----------------|------------|-----|\n",
"|右から走査(in-place)|O(n)|O(1)*|低|★★★|不要|適|*最悪時O(n)|\n",
"|右から走査(immutable)|O(n)|O(n)|低|★★☆|不要|適|常に新規配列生成|\n",
"|文字列変換|O(n)|O(n)|中|★☆☆|str, int組み込み|不適|型変換コスト大|\n",
"|再帰処理|O(n)|O(n)|高|★☆☆|不要|不適|スタック使用|\n",
"|BigInt演算|O(n)|O(n)|低|★★☆|組み込みint|不適|配列長制限なし時のみ有効|\n",
"\n",
"## 3. 採用アルゴリズムと根拠\n",
"\n",
"### 選択理由\n",
"\n",
"**右から走査(in-place)方式**を採用\n",
"\n",
"1. **計算量優位性**: \n",
" - 時間: O(n)で最適、平均的には早期リターンでより高速\n",
" - 空間: ほぼO(1)、最悪ケース（all 9s）のみO(n)\n",
"\n",
"2. **実装効率**: \n",
" - Pythonのリスト操作は直感的\n",
" - 標準的な筆算アルゴリズムで理解容易\n",
" - コード量が少なく保守性高い\n",
"\n",
"3. **保守性**: \n",
" - エッジケースが明確\n",
" - デバッグが容易\n",
" - チーム開発でも理解しやすい\n",
"\n",
"4. **Python特性**: \n",
" - リスト操作はすべてC実装で高速\n",
" - 型アノテーションが自然\n",
" - pylanceとの相性良好\n",
"\n",
"### Python最適化戦略\n",
"\n",
"1. **逆順イテレーション**: `range(len(digits)-1, -1, -1)`でC実装の高速イテレータ活用\n",
"2. **早期リターン**: 繰り上がり不要時に即座に処理終了\n",
"3. **スプレッド演算子**: `[1, *digits]`で効率的なリスト結合\n",
"4. **in-place変更**: LeetCode形式では許容され、メモリ効率的\n",
"\n",
"### トレードオフ\n",
"\n",
"- **可読性 vs パフォーマンス**: in-place変更は可読性を損なわないため両立\n",
"- **型安全性 vs 簡潔性**: 型ヒントを付けても簡潔性は維持\n",
"- **エラーハンドリング vs 速度**: 競プ版ではエラーチェック省略で高速化\n",
"\n",
"## 4. 実装パターン\n",
"\n",
"### 業務開発版（型安全・エラーハンドリング重視）\n",
"Analyze Complexity\n",
"Runtime 0 ms\n",
"Beats 100.00%\n",
"Memory 19.20 MB\n",
"Beats 19.41%\n",
"```python\n",
"from typing import List\n",
"\n",
"class Solution:\n",
" \"\"\"\n",
" Plus One 問題の解決クラス\n",
" \n",
" 大きな整数を表す配列に1を加算する処理を提供\n",
" \"\"\"\n",
" \n",
" def plusOne(self, digits: List[int]) -> List[int]:\n",
" \"\"\"\n",
" 整数配列に1を加算する（業務開発版）\n",
" \n",
" Args:\n",
" digits: 各桁を表す整数リスト（最上位桁が先頭）\n",
" 各要素は0-9の範囲内である必要がある\n",
" \n",
" Returns:\n",
" 1を加算した結果の整数配列\n",
" \n",
" Raises:\n",
" TypeError: 入力が配列でない、または要素が整数でない場合\n",
" ValueError: 配列が空、または要素が0-9の範囲外の場合\n",
" \n",
" Examples:\n",
" >>> Solution().plusOne([1, 2, 3])\n",
" [1, 2, 4]\n",
" >>> Solution().plusOne([9, 9, 9])\n",
" [1, 0, 0, 0]\n",
" \n",
" Time Complexity: O(n) where n = len(digits)\n",
" Space Complexity: O(1) 平均、O(n) 最悪時（all 9s）\n",
" \"\"\"\n",
" # 入力検証\n",
" self._validate_input(digits)\n",
" \n",
" # 右から左へ走査\n",
" for i in range(len(digits) - 1, -1, -1):\n",
" # 現在の桁が9未満の場合\n",
" if digits[i] < 9:\n",
" digits[i] += 1\n",
" return digits # 繰り上がり不要、即座に返却\n",
" \n",
" # 現在の桁が9の場合、0にして繰り上がり継続\n",
" digits[i] = 0\n",
" \n",
" # 全桁が9だった場合（例: [9,9,9] → [1,0,0,0]）\n",
" return [1, *digits]\n",
" \n",
" def _validate_input(self, digits: List[int]) -> None:\n",
" \"\"\"\n",
" 入力配列の検証\n",
" \n",
" Args:\n",
" digits: 検証対象の配列\n",
" \n",
" Raises:\n",
" TypeError: 型が不正な場合\n",
" ValueError: 値が制約を満たさない場合\n",
" \"\"\"\n",
" if not isinstance(digits, list):\n",
" raise TypeError(\"Input must be a list\")\n",
" \n",
" if not digits:\n",
" raise ValueError(\"Input list cannot be empty\")\n",
" \n",
" if len(digits) > 100:\n",
" raise ValueError(\"Input size exceeds constraint (max 100)\")\n",
" \n",
" for i, digit in enumerate(digits):\n",
" if not isinstance(digit, int):\n",
" raise TypeError(f\"Element at index {i} must be an integer\")\n",
" \n",
" if not 0 <= digit <= 9:\n",
" raise ValueError(\n",
" f\"Element at index {i} ({digit}) must be in range [0, 9]\"\n",
" )\n",
Comment on lines +192 to +199

@coderabbitai coderabbitai Bot Jan 25, 2026

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⚠️ Potential issue | 🟡 Minor

🧩 Analysis chain

🏁 Script executed:

find . -name "PlusOne_python.ipynb" -type f

Repository: myoshi2891/Algorithm-DataStructures-Math-SQL

Length of output: 166

🏁 Script executed:

wc -l "./Algorithm/Other/leetcode/66. Plus One/Claude Sonnet 4.5/PlusOne_python.ipynb"

Repository: myoshi2891/Algorithm-DataStructures-Math-SQL

Length of output: 170

🏁 Script executed:

cat -n "./Algorithm/Other/leetcode/66. Plus One/Claude Sonnet 4.5/PlusOne_python.ipynb" | sed -n '180,210p'

Repository: myoshi2891/Algorithm-DataStructures-Math-SQL

Length of output: 1564

🏁 Script executed:

python3 << 'EOF'
# Verify if bool is instance of int in Python
print("isinstance(True, int):", isinstance(True, int))
print("isinstance(False, int):", isinstance(False, int))
print("isinstance(True, bool):", isinstance(True, bool))
print("isinstance(False, bool):", isinstance(False, bool))

# Test the validation logic
digit = True
if not isinstance(digit, int):
    print("Would raise TypeError for True")
else:
    print("True passes isinstance(digit, int) check")

# Test the proposed fix
digit = True
if not isinstance(digit, int) or isinstance(digit, bool):
    print("With fix: True would raise TypeError")
else:
    print("With fix: True would still pass")
EOF

Repository: myoshi2891/Algorithm-DataStructures-Math-SQL

Length of output: 281

bool が整数として通過してしまう入力検証

isinstance(digit, int) を使用していますが、Pythonでは bool は int のサブクラスであるため、True と False が整数として許可されてしまいます。より厳密な型検証が必要な場合は bool を除外してください。

修正案 
-            if not isinstance(digit, int):
+            if not isinstance(digit, int) or isinstance(digit, bool):
                 raise TypeError(f"Element at index {i} must be an integer")
🤖 Prompt for AI Agents 
In `@Algorithm/Other/leetcode/66`. Plus One/Claude Sonnet 4.5/PlusOne_python.ipynb
around lines 192 - 199, The input validation loop over digits incorrectly
accepts booleans because isinstance(digit, int) returns True for bool; update
the check in the loop that currently reads "for i, digit in enumerate(digits):"
to exclude bools—e.g., replace the isinstance(digit, int) check with a strict
type check such as type(digit) is int or add an extra condition like
isinstance(digit, int) and not isinstance(digit, bool) so that True/False are
rejected before the range check in the function handling digits (the loop using
variables i and digit).

" \n",
" # 先頭が0でないことを確認（制約より）\n",
" if len(digits) > 1 and digits[0] == 0:\n",
" raise ValueError(\"Leading zero is not allowed\")\n",
"```\n",
"\n",
"### 競技プログラミング版（パフォーマンス最優先）\n",
"Analyze Complexity\n",
"Runtime 0 ms\n",
"Beats 100.00%\n",
"Memory 19.25 MB\n",
"Beats 17.57%\n",
"```python\n",
"from typing import List\n",
"\n",
"class Solution:\n",
" def plusOne(self, digits: List[int]) -> List[int]:\n",
" \"\"\"\n",
" 整数配列に1を加算する（競プ最適化版）\n",
" \n",
" エラーハンドリング省略、性能最優先\n",
" \n",
" Time Complexity: O(n)\n",
" Space Complexity: O(1) 平均、O(n) 最悪時\n",
" \"\"\"\n",
" # 右から左へ走査（インデックス逆順）\n",
" for i in range(len(digits) - 1, -1, -1):\n",
" if digits[i] < 9:\n",
" digits[i] += 1\n",
" return digits\n",
" digits[i] = 0\n",
" \n",
" # 全桁が9の場合\n",
" return [1, *digits]\n",
"```\n",
"\n",
"### LeetCode提出用（最終版）\n",
"\n",
"```python\n",
"class Solution:\n",
" def plusOne(self, digits: list[int]) -> list[int]:\n",
" \"\"\"\n",
" Time Complexity: O(n)\n",
" Space Complexity: O(1) average, O(n) worst case\n",
" \"\"\"\n",
" for i in range(len(digits) - 1, -1, -1):\n",
" if digits[i] < 9:\n",
" digits[i] += 1\n",
" return digits\n",
" digits[i] = 0\n",
" \n",
" return [1, *digits]\n",
"```\n",
"\n",
"## 5. Python特有の最適化ポイント\n",
"\n",
"### CPython インタープリター最適化\n",
"\n",
"1. **組み込みイテレータ活用**\n",
" ```python\n",
" # range()の逆順イテレーションはC実装で高速\n",
" for i in range(len(digits) - 1, -1, -1):\n",
" ```\n",
"\n",
"2. **リスト操作最適化**\n",
" ```python\n",
" # スプレッド演算子によるリスト結合（Python 3.5+）\n",
" return [1, *digits] # [1] + digits より効率的\n",
" ```\n",
"\n",
"3. **早期リターン**\n",
" ```python\n",
" # 不要なループを回避\n",
" if digits[i] < 9:\n",
" digits[i] += 1\n",
" return digits # 即座に終了\n",
" ```\n",
"\n",
"### データ構造選択の根拠\n",
"\n",
"- **`list`を選択**: \n",
" - インデックスアクセスO(1)\n",
" - 末尾追加O(1)\n",
" - CPythonでC実装、高速\n",
" \n",
"- **`deque`不要**: \n",
" - 先頭挿入は最悪ケースのみ（稀）\n",
" - この問題では`list`で十分\n",
"\n",
"### メモリ最適化\n",
"\n",
"1. **in-place変更**: \n",
" - 新規メモリ確保を最小化\n",
" - LeetCode形式では許容される\n",
" \n",
"2. **スプレッド演算子**: \n",
" - `[1] + digits`はコピーが2回発生\n",
" - `[1, *digits]`は1回で効率的\n",
"\n",
"## 6. 実装の特徴と利点\n",
"\n",
"### 型安全性（pylance対応）\n",
"\n",
"```python\n",
"# Python 3.9+の型ヒント\n",
"def plusOne(self, digits: list[int]) -> list[int]:\n",
" # pylanceで完全な型チェックが可能\n",
" # List[int]より list[int] が推奨（PEP 585）\n",
"```\n",
"\n",
"### エッジケース処理\n",
"\n",
"```python\n",
"# テスト例（実装には含めない）\n",
"# [1,2,3] → [1,2,4] 早期リターン\n",
"# [9] → [1,0] 単一要素、全桁9\n",
"# [1,9,9] → [2,0,0] 部分的繰り上がり\n",
"# [9,9,9] → [1,0,0,0] 全桁9、新規配列生成\n",
"```\n",
"\n",
"### パフォーマンス特性\n",
"\n",
"- **平均ケース**: O(1)～O(k) (kは繰り上がり回数)\n",
"- **最悪ケース**: O(n) (全桁が9)\n",
"- **メモリ**: ほぼO(1)、最悪時のみO(n)\n",
"\n",
"この実装は、Pythonの特性を最大限活用し、可読性とパフォーマンスを両立した最適解となっています。"
]
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