Leetcode 208. 实现 Trie (前缀树)

#define cti(x) (x-'a')
#define itc(x) (x+'a')
const int maxn = 100005;
const int sigma_size = 26;
class Trie {
public:
    /** Initialize your data structure here. */
    int ch[maxn][sigma_size], val[maxn]={}, sz;
    Trie() { sz = 1, memset(ch[0], 0, sizeof(ch[0])); }

    /** Inserts a word into the trie. */
    void insert(string word) {
       int o = 0;
        for (int i = 0; i < word.size(); ++i) {
            if (!ch[o][cti(word[i])])
                memset(ch[sz], 0, sizeof(ch[sz])), val[sz] = 0, ch[o][cti(word[i])] = sz++;
            o = ch[o][cti(word[i])];
        }
        val[o] = 1;
    }

    /** Returns if the word is in the trie. */
    bool search(string word) {
        int o=0;
        for (int i = 0; i < word.size(); ++i){
            if (!ch[o][cti(word[i])]) return false;
            o = ch[o][cti(word[i])];
        }
        return val[o]==1;
    }

    /** Returns if there is any word in the trie that starts with the given prefix. */
    bool startsWith(string prefix) {
        int o=0;
        for (int i = 0; i < prefix.size(); ++i){
            if (!ch[o][cti(prefix[i])]) return false;
            o = ch[o][cti(prefix[i])];
        }
        return true;
    }
};

/**
 * 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);
 */