Several bug fixes and improvements (#945)

* Update Dockerfile for code debugging.

* Format Python code using Black.

* Improve dark theme by defining html classes for the figures, animations and cover images.

* Fix several glossary translation.

* Update a code comment.

* Fix climbing_stairs_backtrack: the pruning should not require the sorted choices list.

* Update the code of array and list traversal.

* Fix a rendering issue of README.md

* Update code of list traversal.

* Fix array_definition.png

* Update README.md

* Fix max_capacity_moving_short_board.png

* Fix array.dart

* Fix array.dart

* Fix array.dart

* Fix array.dart

codes/swift/chapter_array_and_linkedlist/array.swift

@@ -48,12 +48,12 @@ func remove(nums: inout [Int], index: Int) {
 func traverse(nums: [Int]) {
     var count = 0
     // 通过索引遍历数组
-    for _ in nums.indices {
-        count += 1
+    for i in nums.indices {
+        count += nums[i]
     }
-    // 直接遍历数组
-    for _ in nums {
-        count += 1
+    // 直接遍历数组元素
+    for num in nums {
+        count += num
     }
 }
 

codes/swift/chapter_array_and_linkedlist/list.swift

@@ -42,14 +42,13 @@ enum List {
 
         /* 通过索引遍历列表 */
         var count = 0
-        for _ in nums.indices {
-            count += 1
+        for i in nums.indices {
+            count += nums[i]
         }
-
         /* 直接遍历列表元素 */
         count = 0
-        for _ in nums {
-            count += 1
+        for x in nums {
+            count += x
         }
 
         /* 拼接两个列表 */

codes/swift/chapter_dynamic_programming/climbing_stairs_backtrack.swift

@@ -14,7 +14,7 @@ func backtrack(choices: [Int], state: Int, n: Int, res: inout [Int]) {
     for choice in choices {
         // 剪枝：不允许越过第 n 阶
         if state + choice > n {
-            break
+            continue
         }
         backtrack(choices: choices, state: state + choice, n: n, res: &res)
     }