Add dart chapter_computational_complexity (#363)

* add dart chapter_array_and_linkedlist

* update my_list.dart

* update chapter_array_and_linkedlist

* Update my_list.dart

* Update array.dart

* Update file name

* Add chapter_computational_complexity

* Add chapter_computational_complexity

* add space_complexity class and format code

* remove class

---------

Co-authored-by: huangjianqing <huangjianqing@52tt.com>
Co-authored-by: Yudong Jin <krahets@163.com>

codes/dart/utils/PrintUtil.dart

@@ -1,21 +0,0 @@
-/**
- * File: PrintUtil
- * Created Time: 2023-01-23
- * Author: Jefferson (JeffersonHuang77@gmail.com)
- */
-
-import 'ListNode.dart';
-
-class PrintUtil {
-    
-  void printLinkedList(ListNode? head) {
-    List<String> list = [];
-
-    while (head != null) {
-      list.add('${head.val}');
-      head = head.next;
-    }
-
-    print(list.join(' -> '));
-  }
-}

codes/dart/utils/print_util.dart

@@ -0,0 +1,72 @@
+/**
+ * File: PrintUtil
+ * Created Time: 2023-01-23
+ * Author: Jefferson (JeffersonHuang77@gmail.com)
+ */
+import 'dart:io';
+
+import 'list_node.dart';
+import 'tree_node.dart';
+
+class Trunk {
+  Trunk? prev;
+  String str;
+
+  Trunk(this.prev, this.str);
+}
+
+void printLinkedList(ListNode? head) {
+  List<String> list = [];
+
+  while (head != null) {
+    list.add('${head.val}');
+    head = head.next;
+  }
+
+  print(list.join(' -> '));
+}
+/*
+   * Print a binary tree
+   * @param root
+   * @param prev
+   * @param isLeft
+   */
+
+void printTree(TreeNode? root, [Trunk? prev = null, bool isLeft = false]) {
+  if (root == null) {
+    return;
+  }
+
+  String prev_str = '    ';
+  Trunk trunk = Trunk(prev, prev_str);
+
+  printTree(root.right, trunk, true);
+
+  if (prev == null) {
+    trunk.str = '---';
+  } else if (isLeft) {
+    trunk.str = '/---';
+    prev_str = '   |';
+  } else {
+    trunk.str = '\\---';
+    prev.str = prev_str;
+  }
+  showTrunks(trunk);
+  print(' ${root.val}');
+
+  if (prev != null) {
+    prev.str = prev_str;
+  }
+  trunk.str = '   |';
+
+  printTree(root.left, trunk, false);
+}
+
+void showTrunks(Trunk? p) {
+  if (p == null) {
+    return;
+  }
+
+  showTrunks(p.prev);
+  stdout.write(p.str);
+}

codes/dart/utils/tree_node.dart

@@ -0,0 +1,69 @@
+/**
+ * File: tree_node.dart
+ * Created Time: 2023-2-12
+ * Author: Jefferson (JeffersonHuang77@gmail.com)
+ */
+
+import 'dart:collection';
+
+class TreeNode {
+  late int val; // 结点值
+  late int height; // 结点高度
+  late TreeNode? left; // 左子结点引用
+  late TreeNode? right; // 右子结点引用
+
+  TreeNode(int x) {
+    val = x;
+  }
+}
+
+/**
+     * Generate a binary tree given an array
+     * @param list
+     * @return
+     */
+TreeNode? listToTree(List<int> list) {
+  int size = list.length;
+  if (size == 0) return null;
+
+  TreeNode root = TreeNode(list[0]);
+  Queue<TreeNode?> queue = Queue();
+  queue.add(root);
+  int i = 0;
+  while (!queue.isEmpty) {
+    TreeNode? node = queue.first;
+    queue.removeFirst();
+    if (++i >= size) break;
+    node?.left = TreeNode(list[i]);
+    queue.add(node?.left);
+    if (++i >= size) break;
+    node?.left = TreeNode(list[i]);
+    queue.add(node?.right);
+  }
+  return root;
+}
+
+/**
+     * Serialize a binary tree to a list
+     * @param root
+     * @return
+     */
+List<int?> treeToList(TreeNode? root) {
+  List<int?> list = [];
+  if (root == null) return list;
+  Queue<TreeNode?> queue = Queue();
+  queue.add(root);
+
+  while (!queue.isEmpty) {
+    TreeNode? node = queue.first;
+    queue.removeFirst();
+    if (node != null) {
+      list.add(node.val);
+      queue.add(node.left);
+      queue.add(node.right);
+    } else {
+      list.add(null);
+    }
+  }
+  return list;
+}