一刷211

Author: diguage

README.adoc

@@ -1503,12 +1503,12 @@ TIP: **公众号的微信号是: `jikerizhi`**。__因为众所周知的原因
 |Medium
 |
 
-//|{counter:codes}
-//|{leetcode_base_url}/design-add-and-search-words-data-structure/[211. 添加与搜索单词 - 数据结构设计]
-//|{source_base_url}/_0211_DesignAddAndSearchWordsDataStructure.java[Java]
-//|{doc_base_url}/0211-design-add-and-search-words-data-structure.adoc[题解]
-//|Medium
-//|
+|{counter:codes}
+|{leetcode_base_url}/design-add-and-search-words-data-structure/[211. 添加与搜索单词 - 数据结构设计]
+|{source_base_url}/_0211_DesignAddAndSearchWordsDataStructure.java[Java]
+|{doc_base_url}/0211-design-add-and-search-words-data-structure.adoc[题解]
+|Medium
+|
 
 //|{counter:codes}
 //|{leetcode_base_url}/word-search-ii/[212. Word Search II^]

docs/0211-design-add-and-search-words-data-structure.adoc

@@ -41,6 +41,7 @@ wordDictionary.search("b.."); // 返回 True
 
 == 思路分析
 
+前缀树。需要处理通配符的情况，尤其要注意结尾字符的处理。
 
 [[src-0211]]
 [tabs]

docs/index.adoc

@@ -504,7 +504,7 @@ include::0209-minimum-size-subarray-sum.adoc[leveloffset=+1]
 
 include::0210-course-schedule-ii.adoc[leveloffset=+1]
 
-// include::0211-design-add-and-search-words-data-structure.adoc[leveloffset=+1]
+include::0211-design-add-and-search-words-data-structure.adoc[leveloffset=+1]
 
 // include::0212-word-search-ii.adoc[leveloffset=+1]
 

logbook/202503.adoc

@@ -553,6 +553,11 @@ endif::[]
 |{doc_base_url}/0697-degree-of-an-array.adoc[题解]
 |✅
 
+|{counter:codes2503}
+|{leetcode_base_url}/design-add-and-search-words-data-structure/[211. 添加与搜索单词 - 数据结构设计]
+|{doc_base_url}/0211-design-add-and-search-words-data-structure.adoc[题解]
+|✅ 前缀树。需要处理通配符的情况，尤其要注意结尾字符的处理。
+
 |===
 
 截止目前，本轮练习一共完成 {codes2503} 道题。

src/main/java/com/diguage/algo/leetcode/_0211_DesignAddAndSearchWordsDataStructure.java

@@ -0,0 +1,105 @@
+package com.diguage.algo.leetcode;
+
+public class _0211_DesignAddAndSearchWordsDataStructure {
+  // tag::answer[]
+
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2025-04-30 00:08:59
+   */
+  static class WordDictionary {
+    private WordDictionary[] letters;
+    private boolean end = false;
+
+    public WordDictionary() {
+      letters = new WordDictionary[26];
+    }
+
+    public void addWord(String word) {
+      char[] chars = word.toCharArray();
+      WordDictionary current = this;
+      for (int i = 0; i < chars.length; i++) {
+        if (current.letters[chars[i] - 'a'] == null) {
+          current.letters[chars[i] - 'a'] = new WordDictionary();
+        }
+        current = current.letters[chars[i] - 'a'];
+        if (i == chars.length - 1) {
+          current.end = true;
+        }
+      }
+    }
+
+    public boolean search(String word) {
+      char[] chars = word.toCharArray();
+      return backtrack(chars, 0, this);
+    }
+
+    private boolean backtrack(char[] chars, int index,
+                              WordDictionary current) {
+      if (index == chars.length) {
+        return true;
+      }
+      if (chars[index] == '.') {
+        for (int i = 0; i < 26; i++) {
+          if (current.letters[i] == null) {
+            continue;
+          }
+          if (index == chars.length - 1) {
+            if (current.letters[i].end) {
+              return true;
+            } else {
+              continue;
+            }
+          }
+          boolean ok = backtrack(chars, index + 1, current.letters[i]);
+          if (ok) {
+            return true;
+          }
+        }
+        return false;
+      } else {
+        WordDictionary next = current.letters[chars[index] - 'a'];
+        if (next == null) {
+          return false;
+        } else {
+          if (index == chars.length - 1) {
+            return next.end;
+          }
+          return backtrack(chars, index + 1, next);
+        }
+      }
+    }
+  }
+
+  // end::answer[]
+  public static void main(String[] args) {
+    WordDictionary dict = new WordDictionary();
+    // "addWord","addWord","addWord","addWord","search","search","addWord","search","search","search","search","search","search"
+    // ["at"],    ["and"],  ["an"],  ["add"],  ["a"],    [".at"], ["bat"],  [".at"], ["an."], ["a.d."], ["b."], ["a.d"], ["."]
+    dict.addWord("at");
+    dict.addWord("and");
+    dict.addWord("an");
+    dict.addWord("add");
+    dict.search("a");
+    dict.search(".at");
+    dict.search("bat");
+    dict.search(".at");
+    dict.search("an.");
+    dict.search("a.d.");
+    dict.search("b.");
+    dict.search("a.d");
+    dict.search(".");
+    // "addWord","addWord","search","search","search","search","search","search","search","search"
+    // ["a"],    ["ab"],   ["a"],   ["a."],   ["ab"],  [".a"]  ,[".b"],  ["ab."], ["."], [".."]
+//    dict.addWord("a");
+//    dict.addWord("ab");
+//    dict.search("a");
+//    dict.search("a.");
+//    dict.search("ab");
+//    dict.search(".a");
+//    dict.search(".b");
+//    dict.search("ab.");
+//    dict.search(".");
+//    dict.search("..");
+  }
+}