LC 966. Vowel Spellchecker

Given a wordlist, we want to implement a spellchecker that converts a query word into a correct word.

For a given query word, the spell checker handles two categories of spelling mistakes:

Capitalization: If the query matches a word in the wordlist (case-insensitive), then the query word is returned with the same case as the case in the wordlist.
- Example: wordlist = ["yellow"], query = "YellOw": correct = "yellow"
- Example: wordlist = ["Yellow"], query = "yellow": correct = "Yellow"
- Example: wordlist = ["yellow"], query = "yellow": correct = "yellow"
Vowel Errors: If after replacing the vowels ('a', 'e', 'i', 'o', 'u') of the query word with any vowel individually, it matches a word in the wordlist (case-insensitive), then the query word is returned with the same case as the match in the wordlist.
- Example: wordlist = ["YellOw"], query = "yollow": correct = "YellOw"
- Example: wordlist = ["YellOw"], query = "yeellow": correct = "" (no match)
- Example: wordlist = ["YellOw"], query = "yllw": correct = "" (no match)

In addition, the spell checker operates under the following precedence rules:

When the query exactly matches a word in the wordlist (case-sensitive), you should return the same word back.
When the query matches a word up to capitlization, you should return the first such match in the wordlist.
When the query matches a word up to vowel errors, you should return the first such match in the wordlist.
If the query has no matches in the wordlist, you should return the empty string.

Given some queries, return a list of words answer, where answer[i] is the correct word for query = queries[i].

Example 1:

Input: wordlist = ["KiTe","kite","hare","Hare"], queries = ["kite","Kite","KiTe","Hare","HARE","Hear","hear","keti","keet","keto"]
Output: ["kite","KiTe","KiTe","Hare","hare","","","KiTe","","KiTe"]

Note:

1 <= wordlist.length <= 5000
1 <= queries.length <= 5000
1 <= wordlist[i].length <= 7
1 <= queries[i].length <= 7
All strings in wordlist and queries consist only of english letters.

踩坑踩了一个下午，掉到坑里出不来了。

Runtime: 96 ms, faster than 100.00% of C++ online submissions for Vowel Spellchecker.

第一种是我的做法修改了TrieNode的结构，让它带了一个case_sensitive的标志位。如果带上大小写搜索，

每次需要判断字符的大小写，这样得到的是第一种准确的搜索。如果不敏感，就全部放在小写的这个节点里。

为了满足题意，大小写不敏感的可能有多种，那么Trie节点带一个数组比较合适。

注意：

1. 本来的字典可能有重复，我去。。。

2. 需要返回最小的index，那就把所有的求出来以后再求最小的index。

写了一个下午。

class TrieNode{
public:
  string word;
  vector<string> wordlist;
  TrieNode* lowercase[26];
  TrieNode* uppercase[26];
  TrieNode(){
    for(int i=0; i<26; i++) lowercase[i] = nullptr;
    for(int i=0; i<26; i++) uppercase[i] = nullptr;
  }
};

class Trie{
public:
  TrieNode* root;
  Trie(const vector<string>& wordlist, bool case_sensitive = true){
    root = new TrieNode();
    BuildTrie(wordlist, case_sensitive);
  }
  void BuildTrie(const vector<string>& wordlist, bool case_sensitive = true){

    for(int i=0; i<wordlist.size(); i++){
      TrieNode* tmp = root;
      for(int j=0; j<wordlist[i].size(); j++){
        char tmpchar = wordlist[i][j];
        int idx = 0;
        if(!case_sensitive){
          if(tmpchar >= 'A' && tmpchar <= 'Z'){
            idx = tmpchar - 'A';
          }else idx = tmpchar - 'a';
          if(!tmp->lowercase[idx]) tmp->lowercase[idx] = new TrieNode();
          tmp = tmp->lowercase[idx];
        }else{
          if(tmpchar >= 'A' && tmpchar <= 'Z'){
            idx = tmpchar - 'A';
            if(!tmp->uppercase[idx]) tmp->uppercase[idx] = new TrieNode();
            tmp = tmp->uppercase[idx];
          }else {
            idx = tmpchar - 'a';
            if(!tmp->lowercase[idx]) tmp->lowercase[idx] = new TrieNode();
            tmp = tmp->lowercase[idx];
          }
        }
      }
      if(case_sensitive){
        tmp->word = wordlist[i];
      }else {
        tmp->wordlist.push_back(wordlist[i]);
      }
    }
  }
  bool hasword(string word, string& foundword, bool case_sensitive = true){
    TrieNode* tmp = root;
    locale loc;
    for(int i=0; i<word.size(); i++){
      char tmpchar = word[i];
      int idx = 0;
      if(!case_sensitive){
        tmpchar = tolower(tmpchar, loc);
        idx = tmpchar - 'a';
        if(!tmp->lowercase[idx]) return false;
        tmp = tmp->lowercase[idx];
      }else {
        if(tmpchar >= 'A' && tmpchar <= 'Z') {
          idx = tmpchar - 'A';
          if(!tmp->uppercase[idx]) return false;
          tmp = tmp->uppercase[idx];
        } else {
          idx = tmpchar - 'a';
          if(!tmp->lowercase[idx]) return false;
          tmp = tmp->lowercase[idx];
        }
      }
    }
    if(!case_sensitive) {
      if(!tmp->wordlist.empty()){
        foundword = tmp->wordlist[0];
        return true;
      }
      return false;
    }
    if(!tmp->word.empty()) {
      foundword = tmp->word;
      return true;
    }
    return false;
  }
};

class Solution {
public:
  set<char> vset;
  unordered_map<string,int> mp;
  vector<string> spellchecker(vector<string>& wordlist, vector<string>& queries) {
    for(int i=0; i<wordlist.size(); i++){
      mp[wordlist[i]] = i;
    }
    vset.insert('a');vset.insert('e');vset.insert('i');
    vset.insert('o');vset.insert('u');
    vector<string> ret;
    Trie trie_case_sensi = Trie(wordlist);
    Trie trie_not_case_sensi = Trie(wordlist, false);
    for(int i=0; i<queries.size(); i++){
      string foundword;
      vector<string> foundwordvec;
      if(trie_case_sensi.hasword(queries[i],foundword)) {
        ret.push_back(queries[i]);
      }else if(trie_not_case_sensi.hasword(queries[i], foundword, false)){
        ret.push_back(foundword);
      }else {
        dfs(trie_not_case_sensi.root, queries[i], foundwordvec, 0);
        int minidx = wordlist.size();
        for(auto x : foundwordvec) minidx = min(minidx, mp[x]);
        if(minidx == wordlist.size()) ret.push_back("");
        else ret.push_back(wordlist[minidx]);
      }
    }
    return ret;
  }

  void dfs(const TrieNode* root,string query, vector<string>& ret, int start){
    if(start == query.size()){
      assert(!root->wordlist.empty());
      ret.push_back(root->wordlist[0]);
      return ;
    }
    std::locale loc;
    char c = tolower(query[start],loc);
    int idx = 0;
    idx = c - 'a';
    if(vset.count(c)){
      for(auto it = vset.begin(); it != vset.end(); it++){
        char vsub = *it;
        int newidx = 0;
        newidx = vsub - 'a';
        if(!root->lowercase[newidx]) continue;
        TrieNode* nextroot = root->lowercase[newidx];
        dfs(nextroot, query, ret, start+1);
      }
    }else{
      if(!root->lowercase[idx]) return ;
      TrieNode* nextroot = root->lowercase[idx];
      dfs(nextroot, query, ret, start+1);
    }
  }
};

下面看看网上的大神的解法，很简单，既然aeiou都能互相匹配，那就把aeiou变成#，这样一来不就行了么！真是厉害。

class Solution {
    public String[] spellchecker(String[] wordlist, String[] queries) {
        Set<String> words = new HashSet<>(Arrays.asList(wordlist));
        HashMap<String, String> cap = new HashMap<>();
        HashMap<String, String> vowel = new HashMap<>();
        for (String w : wordlist) {
            String lower = w.toLowerCase(), devowel = lower.replaceAll("[aeiou]", "#");
            cap.putIfAbsent(lower, w);
            vowel.putIfAbsent(devowel, w);
        }
        for (int i = 0; i < queries.length; ++i) {
            if (words.contains(queries[i])) continue;
            String lower = queries[i].toLowerCase(), devowel = lower.replaceAll("[aeiou]", "#");
            if (cap.containsKey(lower)) {
                queries[i] = cap.get(lower);
            } else if (vowel.containsKey(devowel)) {
                queries[i] = vowel.get(devowel);
            } else {
                queries[i] = "";
            }
        }
        return queries;
    }
}

LC 966. Vowel Spellchecker

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