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.

---------

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

ja/codes/python/chapter_tree/binary_tree_dfs.py

@@ -0,0 +1,65 @@
+"""
+File: binary_tree_dfs.py
+Created Time: 2022-12-20
+Author: a16su (lpluls001@gmail.com)
+"""
+
+import sys
+from pathlib import Path
+
+sys.path.append(str(Path(__file__).parent.parent))
+from modules import TreeNode, list_to_tree, print_tree
+
+
+def pre_order(root: TreeNode | None):
+    """前順走査"""
+    if root is None:
+        return
+    # 訪問順序: ルートノード -> 左部分木 -> 右部分木
+    res.append(root.val)
+    pre_order(root=root.left)
+    pre_order(root=root.right)
+
+
+def in_order(root: TreeNode | None):
+    """中順走査"""
+    if root is None:
+        return
+    # 訪問順序: 左部分木 -> ルートノード -> 右部分木
+    in_order(root=root.left)
+    res.append(root.val)
+    in_order(root=root.right)
+
+
+def post_order(root: TreeNode | None):
+    """後順走査"""
+    if root is None:
+        return
+    # 訪問順序: 左部分木 -> 右部分木 -> ルートノード
+    post_order(root=root.left)
+    post_order(root=root.right)
+    res.append(root.val)
+
+
+"""ドライバコード"""
+if __name__ == "__main__":
+    # 二分木を初期化
+    # 特定の関数を使用して配列を二分木に変換
+    root = list_to_tree(arr=[1, 2, 3, 4, 5, 6, 7])
+    print("\n二分木を初期化\n")
+    print_tree(root)
+
+    # 前順走査
+    res = []
+    pre_order(root)
+    print("\n前順走査のノードシーケンスを出力 = ", res)
+
+    # 中順走査
+    res.clear()
+    in_order(root)
+    print("\n中順走査のノードシーケンスを出力 = ", res)
+
+    # 後順走査
+    res.clear()
+    post_order(root)
+    print("\n後順走査のノードシーケンスを出力 = ", res)