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/java/chapter_dynamic_programming/climbing_stairs_dp.java

@@ -0,0 +1,48 @@
+/**
+ * File: climbing_stairs_dp.java
+ * Created Time: 2023-06-30
+ * Author: krahets (krahets@163.com)
+ */
+
+package chapter_dynamic_programming;
+
+public class climbing_stairs_dp {
+    /* 階段登り：動的プログラミング */
+    public static int climbingStairsDP(int n) {
+        if (n == 1 || n == 2)
+            return n;
+        // DPテーブルを初期化し、部分問題の解を格納するために使用
+        int[] dp = new int[n + 1];
+        // 初期状態：最小の部分問題の解を事前設定
+        dp[1] = 1;
+        dp[2] = 2;
+        // 状態遷移：小さな問題から大きな部分問題を段階的に解く
+        for (int i = 3; i <= n; i++) {
+            dp[i] = dp[i - 1] + dp[i - 2];
+        }
+        return dp[n];
+    }
+
+    /* 階段登り：空間最適化動的プログラミング */
+    public static int climbingStairsDPComp(int n) {
+        if (n == 1 || n == 2)
+            return n;
+        int a = 1, b = 2;
+        for (int i = 3; i <= n; i++) {
+            int tmp = b;
+            b = a + b;
+            a = tmp;
+        }
+        return b;
+    }
+
+    public static void main(String[] args) {
+        int n = 9;
+
+        int res = climbingStairsDP(n);
+        System.out.println(String.format("%d段の階段を登る解は%d通りです", n, res));
+
+        res = climbingStairsDPComp(n);
+        System.out.println(String.format("%d段の階段を登る解は%d通りです", n, res));
+    }
+}