-
Notifications
You must be signed in to change notification settings - Fork 95
/
implement-trie-prefix-tree.cpp
77 lines (66 loc) · 1.69 KB
/
implement-trie-prefix-tree.cpp
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
75
76
77
class TrieNode {
public:
// Initialize your data structure here.
TrieNode() {
count = 0;
for (int i = 0; i < 26; ++i) {
next[i] = NULL;
}
}
int count;
TrieNode* next[26];
};
class Trie {
public:
Trie() {
root = new TrieNode();
}
~Trie() {
this->deleteNodes(root);
}
// Inserts a word into the trie.
void insert(string key) {
TrieNode* cur = this->root;
for (size_t i = 0; i < key.size(); ++i) {
if (cur->next[key[i]-'a'] == NULL) {
cur->next[key[i]-'a'] = new TrieNode();
}
cur = cur->next[key[i]-'a'];
}
++cur->count;
}
// Returns if the word is in the trie.
bool search(string key) {
return getTargetCount(key) > 0;
}
// Returns if there is any word in the trie
// that starts with the given prefix.
bool startsWith(string prefix) {
return this->getTargetCount(prefix) != -1;
}
void deleteNodes(TrieNode* node) {
if (node == NULL) {
return;
}
for (size_t i = 0; i < 26; ++i) {
this->deleteNodes(node->next[i]);
}
delete node;
}
private:
int getTargetCount(string key) {
TrieNode* cur = this->root;
for (size_t i = 0; i < key.size(); ++i) {
if (cur->next[key[i]-'a'] == NULL) {
return -1;
}
cur = cur->next[key[i]-'a'];
}
return cur->count;
}
TrieNode* root;
};
// Your Trie object will be instantiated and called as such:
// Trie trie;
// trie.insert("somestring");
// trie.search("key");