Trie for string LeetCode

Trie build and search 

class TrieNode
{
public:
    TrieNode * next[26];
    bool is_word;
    TrieNode(bool b = false)
    {
        memset(next,0,sizeof(next));
        is_word = b;
    }
};
class Trie {
    TrieNode* root;
public:
    /** Initialize your data structure here. */
    Trie() {
        root = new TrieNode();
    }
    
    /** Inserts a word into the trie. */
    void insert(string word) {
        TrieNode* p = root;
        for(int i=0;i<word.size();i++)
        {
            if(p->next[word[i]-'a']==NULL)
                p->next[word[i]-'a']=new TrieNode();
            p = p->next[word[i]-'a'];
        }
        p->is_word=true;
    }
    
    /** Returns if the word is in the trie. */
    bool search(string word) {
        TrieNode* p = find(word);
        return p&&p->is_word;
    }
    
    /** Returns if there is any word in the trie that starts with the given prefix. */
    bool startsWith(string prefix) {
        return find(prefix);
    }
    
    TrieNode* find(string word)
    {
        TrieNode* p = root;
        for(int i=0;i<word.size();i++)
            if(p->next[word[i]-'a']==NULL)return NULL;
            else p=p->next[word[i]-'a'];
        return p;
    }
};

/**
 * Your Trie object will be instantiated and called as such:
 * Trie obj = new Trie();
 * obj.insert(word);
 * bool param_2 = obj.search(word);
 * bool param_3 = obj.startsWith(prefix);
 */

加 . 正则匹配一个任意字母 ，递归处理，注意p应指向当前遍历字母对应的结点

class TrieNode
{
public:
    TrieNode *next[26];
    bool is_word;

    TrieNode(bool b = false)
    {
        memset(next, 0, sizeof(next));
        is_word = b;
    }
};

class WordDictionary {
public:
    /** Initialize your data structure here. */
    WordDictionary() {
        root = new TrieNode();
    }

    /** Adds a word into the data structure. */
    void addWord(string word) {
        TrieNode *p = root;
        for (int i = 0; i < word.size(); i++)
        {
            if (p->next[word[i] - 'a'] == NULL)
                p->next[word[i] - 'a'] = new TrieNode();
            p = p->next[word[i] - 'a'];
        }
        p->is_word = true;
    }

    /** Returns if the word is in the data structure. A word could contain the dot character '.' to represent any one letter. */
    bool search(string word) {
        return query(word.c_str(), root);
    }

private:
    TrieNode* root;
    bool query(const char* word, TrieNode* node) 
    {
        TrieNode* p = node;
        for (int i = 0; word[i]; i++) 
        {
            if (p && word[i] != '.')
                p = p ->next[word[i] - 'a'];
            else if (p && word[i] == '.')
            { 
                TrieNode* tmp=p;
                for (int j = 0; j < 26; j++)
                {
                    p = tmp -> next[j];
                    if (query(word + i + 1, p))
                        return true;
                }
            }
            else break;
        }
        return p && p -> is_word; 
    }
};
/**
 * Your WordDictionary object will be instantiated and called as such:
 * WordDictionary obj = new WordDictionary();
 * obj.addWord(word);
 * bool param_2 = obj.search(word);
 */

word search II

1. word list insert to Trie

2. dfs search

class TrieNode
{
public:
    TrieNode *next[26];
    string word;

    TrieNode()
    {
        memset(next, 0, sizeof(next));
        word = "";
    }
};

class Trie
{
    
public:
    TrieNode* root;
    Trie()
    {
        root = new TrieNode();
    }

    void insert(string s)
    {
        TrieNode *p = root;
        for (int i = 0; i < s.size(); i++)
        {
            if (p->next[s[i] - 'a'] == NULL)
                p->next[s[i] - 'a'] = new TrieNode();
            p = p->next[s[i] - 'a'];
        }
        p->word = s;
    }

};

void dfs(int i, int j, TrieNode* p, vector<vector<char>>& board, vector<string> &res)
{
    char c = board[i][j];
    if (c == '#' || p->next[c - 'a'] == NULL)return;
    p = p->next[c - 'a'];
    if (p->word != "")
    {
        res.push_back(p->word);//找到
        p->word = "";//去重
    }
    board[i][j] = '#';
    if (i > 0)dfs(i - 1, j, p, board, res);
    if (j > 0)dfs(i, j - 1, p, board, res);
    if (i < board.size() - 1)dfs(i + 1, j, p, board, res);
    if (j < board[0].size() - 1)dfs(i, j + 1, p, board, res);
    board[i][j] = c;
}

class Solution {
public:
    vector<string> findWords(vector<vector<char>>& board, vector<string>& words) {
        Trie t;
        vector<string> res;
        for (int i = 0; i < words.size(); i++)
            t.insert(words[i]);
        for (int i = 0; i < board.size(); i++)
        for (int j = 0; j < board[0].size(); j++)
            dfs(i, j, t.root, board, res);
        return res;
    }
};

 421 数组中任意两个数的最大异或值

思路：建树插入所有数，对每个数按位查找异或值

class Trie{
public:
    Trie* children[2];
    Trie(){
        children[0]=NULL;
        children[1]=NULL;
    }
};

class Solution {
public:
int findMaximumXOR(vector<int>& nums) {
    if(nums.size()==0)return 0;
    //Init Trie
    Trie* root = new Trie();
    for(int num:nums)
    {
        Trie* curNode = root;
        for(int i=31;i>=0;i--)
        {
            int curBit = (num>>i)&1;
            if(curNode->children[curBit]==NULL)
            {
                curNode->children[curBit] = new Trie();
            }
            curNode = curNode->children[curBit];
        }
    }
    int _max = 0xffffffff;
    for(int num:nums)
    {
        Trie* curNode = root;
        int curSum = 0;
        for(int i=31;i>=0;i--)
        {
            int curBit = (num>>i)&1;
            if(curNode->children[curBit^1]!=NULL)
            {
                curSum += 1<<i;
                curNode = curNode->children[curBit^1];
            }
            else
            {
                curNode = curNode->children[curBit];
            }
        }
        _max = max(curSum,_max);
    }
    return _max;
}
    

};