diff --git a/src/main/java/leetcode/editor/cn/Z1R5dt.java b/src/main/java/leetcode/editor/cn/Z1R5dt.java
new file mode 100644
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+++ b/src/main/java/leetcode/editor/cn/Z1R5dt.java
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+//<p>实现一个 <code>MapSum</code> 类，支持两个方法，<code>insert</code>&nbsp;和&nbsp;<code>sum</code>：</p>
+//
+//<ul>
+//	<li><code>MapSum()</code> 初始化 <code>MapSum</code> 对象</li>
+//	<li><code>void insert(String key, int val)</code> 插入 <code>key-val</code> 键值对，字符串表示键 <code>key</code> ，整数表示值 <code>val</code> 。如果键 <code>key</code> 已经存在，那么原来的键值对将被替代成新的键值对。</li>
+//	<li><code>int sum(string prefix)</code> 返回所有以该前缀 <code>prefix</code> 开头的键 <code>key</code> 的值的总和。</li>
+//</ul>
+//
+//<p>&nbsp;</p>
+//
+//<p><strong>示例：</strong></p>
+//
+//<pre>
+//<strong>输入：</strong>
+//inputs = [&quot;MapSum&quot;, &quot;insert&quot;, &quot;sum&quot;, &quot;insert&quot;, &quot;sum&quot;]
+//inputs = [[], [&quot;apple&quot;, 3], [&quot;ap&quot;], [&quot;app&quot;, 2], [&quot;ap&quot;]]
+//<strong>输出：</strong>
+//[null, null, 3, null, 5]
+//
+//<strong>解释：</strong>
+//MapSum mapSum = new MapSum();
+//mapSum.insert(&quot;apple&quot;, 3);  
+//mapSum.sum(&quot;ap&quot;);           // return 3 (<u>ap</u>ple = 3)
+//mapSum.insert(&quot;app&quot;, 2);    
+//mapSum.sum(&quot;ap&quot;);           // return 5 (<u>ap</u>ple + <u>ap</u>p = 3 + 2 = 5)
+//</pre>
+//
+//<p>&nbsp;</p>
+//
+//<p><strong>提示：</strong></p>
+//
+//<ul>
+//	<li><code>1 &lt;= key.length, prefix.length &lt;= 50</code></li>
+//	<li><code>key</code> 和 <code>prefix</code> 仅由小写英文字母组成</li>
+//	<li><code>1 &lt;= val &lt;= 1000</code></li>
+//	<li>最多调用 <code>50</code> 次 <code>insert</code> 和 <code>sum</code></li>
+//</ul>
+//
+//<p>&nbsp;</p>
+//
+//<p><meta charset="UTF-8" />注意：本题与主站 677&nbsp;题相同：&nbsp;<a href="https://leetcode-cn.com/problems/map-sum-pairs/">https://leetcode-cn.com/problems/map-sum-pairs/</a></p>
+//<div><div>Related Topics</div><div><li>设计</li><li>字典树</li><li>哈希表</li><li>字符串</li></div></div><br><div><li>👍 16</li><li>👎 0</li></div>
+package leetcode.editor.cn;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+// 剑指 Offer II 066:单词之和
+public class Z1R5dt {
+    public static void main(String[] args) {
+        Solution solution = new Z1R5dt().new Solution();
+        // TO TEST
+    }
+
+    //leetcode submit region begin(Prohibit modification and deletion)
+    class MapSum {
+        Map<String, Integer> map;
+
+        public MapSum() {
+            map = new HashMap<>();
+        }
+
+        public void insert(String key, int val) {
+            map.put(key, val);
+        }
+
+        public int sum(String prefix) {
+            int res = 0;
+            for (String key : map.keySet()) {
+                if (key.startsWith(prefix)) {
+                    res += map.get(key);
+                }
+            }
+            return res;
+        }
+    }
+
+/**
+ * Your MapSum object will be instantiated and called as such:
+ * MapSum obj = new MapSum();
+ * obj.insert(key,val);
+ * int param_2 = obj.sum(prefix);
+ */
+//leetcode submit region end(Prohibit modification and deletion)
+
+}
diff --git a/src/main/java/leetcode/editor/cn/doc/content/Z1R5dt.md b/src/main/java/leetcode/editor/cn/doc/content/Z1R5dt.md
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index 0000000..61dc852
--- /dev/null
+++ b/src/main/java/leetcode/editor/cn/doc/content/Z1R5dt.md
@@ -0,0 +1,42 @@
+<p>实现一个 <code>MapSum</code> 类，支持两个方法，<code>insert</code>&nbsp;和&nbsp;<code>sum</code>：</p>
+
+<ul>
+	<li><code>MapSum()</code> 初始化 <code>MapSum</code> 对象</li>
+	<li><code>void insert(String key, int val)</code> 插入 <code>key-val</code> 键值对，字符串表示键 <code>key</code> ，整数表示值 <code>val</code> 。如果键 <code>key</code> 已经存在，那么原来的键值对将被替代成新的键值对。</li>
+	<li><code>int sum(string prefix)</code> 返回所有以该前缀 <code>prefix</code> 开头的键 <code>key</code> 的值的总和。</li>
+</ul>
+
+<p>&nbsp;</p>
+
+<p><strong>示例：</strong></p>
+
+<pre>
+<strong>输入：</strong>
+inputs = [&quot;MapSum&quot;, &quot;insert&quot;, &quot;sum&quot;, &quot;insert&quot;, &quot;sum&quot;]
+inputs = [[], [&quot;apple&quot;, 3], [&quot;ap&quot;], [&quot;app&quot;, 2], [&quot;ap&quot;]]
+<strong>输出：</strong>
+[null, null, 3, null, 5]
+
+<strong>解释：</strong>
+MapSum mapSum = new MapSum();
+mapSum.insert(&quot;apple&quot;, 3);  
+mapSum.sum(&quot;ap&quot;);           // return 3 (<u>ap</u>ple = 3)
+mapSum.insert(&quot;app&quot;, 2);    
+mapSum.sum(&quot;ap&quot;);           // return 5 (<u>ap</u>ple + <u>ap</u>p = 3 + 2 = 5)
+</pre>
+
+<p>&nbsp;</p>
+
+<p><strong>提示：</strong></p>
+
+<ul>
+	<li><code>1 &lt;= key.length, prefix.length &lt;= 50</code></li>
+	<li><code>key</code> 和 <code>prefix</code> 仅由小写英文字母组成</li>
+	<li><code>1 &lt;= val &lt;= 1000</code></li>
+	<li>最多调用 <code>50</code> 次 <code>insert</code> 和 <code>sum</code></li>
+</ul>
+
+<p>&nbsp;</p>
+
+<p><meta charset="UTF-8" />注意：本题与主站 677&nbsp;题相同：&nbsp;<a href="https://leetcode-cn.com/problems/map-sum-pairs/">https://leetcode-cn.com/problems/map-sum-pairs/</a></p>
+<div><div>Related Topics</div><div><li>设计</li><li>字典树</li><li>哈希表</li><li>字符串</li></div></div><br><div><li>👍 16</li><li>👎 0</li></div>
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