leet_code_cpp/implement_trie.cpp at main · PDKhan/leet_code_cpp · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
class TrieNode{
public:
    TrieNode* children[26];
    bool isEnd;

    TrieNode(){
        isEnd = false;

        for(int i = 0; i < 26; i++)
            children[i] = nullptr;
    }
};

class Trie {
public:
    TrieNode* root;

    Trie() {
        root = new TrieNode();
    }

    void insert(string word) {
        TrieNode* node = root;

        for(int i = 0; i < word.length(); i++){
            int idx = word[i] - 'a';

            if(!node->children[idx])
                node->children[idx] = new TrieNode();

            node = node->children[idx];
        }

        node->isEnd = true;
    }

    bool search(string word) {
        TrieNode* node = root;

        for(int i = 0; i < word.length(); i++){
            int idx = word[i] - 'a';

            if(!node->children[idx])
                return false;

            node = node->children[idx];
        }

        return node->isEnd;
    }

    bool startsWith(string prefix) {
        TrieNode* node = root;

        for(int i = 0; i < prefix.length(); i++){
            int idx = prefix[i] - 'a';

            if(!node->children[idx])
                return false;

            node = node->children[idx];
        }

        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);
 */