feat: add dart code for chapter_stack_and_queue and chapter_hashing (#445)

* feat: add dart code for chapter stack and queue

* feat: add dart code for chapter_hashing

* Update array_hash_map.dart

codes/dart/chapter_hashing/array_hash_map.dart

@@ -0,0 +1,126 @@
+/**
+ * File: array_hash_map.dart
+ * Created Time: 2023-03-29
+ * Author: liuyuxin (gvenusleo@gmail.com)
+ */
+
+/* 键值对 int -> String */
+class Entry {
+  int key;
+  String val;
+  Entry(this.key, this.val);
+}
+
+/* 基于数组简易实现的哈希表 */
+class ArrayHashMap {
+  late List<Entry?> _buckets;
+
+  ArrayHashMap() {
+    // 初始化数组，包含 100 个桶
+    _buckets = List.filled(100, null);
+  }
+
+  /* 哈希函数 */
+  int _hashFunc(int key) {
+    final int index = key % 100;
+    return index;
+  }
+
+  /* 查询操作 */
+  String? get(int key) {
+    final int index = _hashFunc(key);
+    final Entry? pair = _buckets[index];
+    if (pair == null) {
+      return null;
+    }
+    return pair.val;
+  }
+
+  /* 添加操作 */
+  void put(int key, String val) {
+    final Entry pair = Entry(key, val);
+    final int index = _hashFunc(key);
+    _buckets[index] = pair;
+  }
+
+  /* 删除操作 */
+  void remove(int key) {
+    final int index = _hashFunc(key);
+    _buckets[index] = null;
+  }
+
+  /* 获取所有键值对 */
+  List<Entry> entrySet() {
+    List<Entry> entrySet = [];
+    for (final Entry? pair in _buckets) {
+      if (pair != null) {
+        entrySet.add(pair);
+      }
+    }
+    return entrySet;
+  }
+
+  /* 获取所有键 */
+  List<int> keySet() {
+    List<int> keySet = [];
+    for (final Entry? pair in _buckets) {
+      if (pair != null) {
+        keySet.add(pair.key);
+      }
+    }
+    return keySet;
+  }
+
+  /* 获取所有值 */
+  List<String> values() {
+    List<String> valueSet = [];
+    for (final Entry? pair in _buckets) {
+      if (pair != null) {
+        valueSet.add(pair.val);
+      }
+    }
+    return valueSet;
+  }
+
+  /* 打印哈希表 */
+  void printHashMap() {
+    for (final Entry kv in entrySet()) {
+      print("${kv.key} -> ${kv.val}");
+    }
+  }
+}
+
+/* Driver Code */
+void main() {
+  /* 初始化哈希表 */
+  final ArrayHashMap map = ArrayHashMap();
+
+  /* 添加操作 */
+  // 在哈希表中添加键值对 (key, value)
+  map.put(12836, "小哈");
+  map.put(15937, "小啰");
+  map.put(16750, "小算");
+  map.put(13276, "小法");
+  map.put(10583, "小鸭");
+  print("\n添加完成后，哈希表为\nKey -> Value");
+  map.printHashMap();
+
+  /* 查询操作 */
+  // 向哈希表输入键 key ，得到值 value
+  String? name = map.get(15937);
+  print("\n输入学号 15937 ，查询到姓名 $name");
+
+  /* 删除操作 */
+  // 在哈希表中删除键值对 (key, value)
+  map.remove(10583);
+  print("\n删除 10583 后，哈希表为\nKey -> Value");
+  map.printHashMap();
+
+  /* 遍历哈希表 */
+  print("\n遍历键值对 Key->Value");
+  map.entrySet().forEach((kv) => print("${kv.key} -> ${kv.val}"));
+  print("\n单独遍历键 Key");
+  map.keySet().forEach((key) => print("$key"));
+  print("\n单独遍历值 Value");
+  map.values().forEach((val) => print("$val"));
+}