docs: add Japanese translate documents (#1812)

* docs: add Japanese documents (`ja/docs`)

* docs: add Japanese documents (`ja/codes`)

* docs: add Japanese documents

* Remove pythontutor blocks in ja/

* Add an empty at the end of each markdown file.

* Add the missing figures (use the English version temporarily).

* Add index.md for Japanese version.

* Add index.html for Japanese version.

* Add missing index.assets

* Fix backtracking_algorithm.md for Japanese version.

* Add avatar_eltociear.jpg. Fix image links on the Japanese landing page.

* Add the Japanese banner.

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Co-authored-by: krahets <krahets@163.com>

ja/codes/python/chapter_graph/graph_dfs.py

@@ -0,0 +1,57 @@
+"""
+File: graph_dfs.py
+Created Time: 2023-02-23
+Author: krahets (krahets@163.com)
+"""
+
+import sys
+from pathlib import Path
+
+sys.path.append(str(Path(__file__).parent.parent))
+from modules import Vertex, vets_to_vals, vals_to_vets
+from graph_adjacency_list import GraphAdjList
+
+
+def dfs(graph: GraphAdjList, visited: set[Vertex], res: list[Vertex], vet: Vertex):
+    """深さ優先走査のヘルパー関数"""
+    res.append(vet)  # 訪問済み頂点を記録
+    visited.add(vet)  # 頂点を訪問済みとしてマーク
+    # その頂点のすべての隣接頂点を走査
+    for adjVet in graph.adj_list[vet]:
+        if adjVet in visited:
+            continue  # 既に訪問済みの頂点をスキップ
+        # 隣接頂点を再帰的に訪問
+        dfs(graph, visited, res, adjVet)
+
+
+def graph_dfs(graph: GraphAdjList, start_vet: Vertex) -> list[Vertex]:
+    """深さ優先走査"""
+    # 隣接リストを使用してグラフを表現し、指定された頂点のすべての隣接頂点を取得
+    # 頂点走査シーケンス
+    res = []
+    # ハッシュセット、訪問済み頂点を記録するために使用
+    visited = set[Vertex]()
+    dfs(graph, visited, res, start_vet)
+    return res
+
+
+"""ドライバコード"""
+if __name__ == "__main__":
+    # 無向グラフを初期化
+    v = vals_to_vets([0, 1, 2, 3, 4, 5, 6])
+    edges = [
+        [v[0], v[1]],
+        [v[0], v[3]],
+        [v[1], v[2]],
+        [v[2], v[5]],
+        [v[4], v[5]],
+        [v[5], v[6]],
+    ]
+    graph = GraphAdjList(edges)
+    print("\n初期化後、グラフは")
+    graph.print()
+
+    # 深さ優先走査
+    res = graph_dfs(graph, v[0])
+    print("\n深さ優先走査（DFS）の頂点シーケンスは")
+    print(vets_to_vals(res))