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208. Implement Trie (Prefix Tree) 💫 #72
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72 changes: 72 additions & 0 deletions
src/0208_implement_trie_prefix_tree/impltrie.go
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,72 @@ | ||
| /* | ||
| 208. Implement Trie (Prefix Tree) | ||
| https://leetcode.com/problems/implement-trie-prefix-tree/ | ||
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| Implement a trie with insert, search, and startsWith methods. | ||
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| Note: | ||
| You may assume that all inputs are consist of lowercase letters a-z. | ||
| All inputs are guaranteed to be non-empty strings. | ||
| */ | ||
| // time: 2019年01月31日 | ||
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| package impltree | ||
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| type node struct { | ||
| isWord bool | ||
| next map[byte]*node | ||
| } | ||
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| // Trie prefix tree | ||
| type Trie struct { | ||
| root *node | ||
| size int | ||
| } | ||
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| // Constructor initialize data structure here. | ||
| func Constructor() Trie { | ||
| return Trie{root: &node{next: make(map[byte]*node)}} | ||
| } | ||
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| // Insert inserts a word into the trie. | ||
| func (trie *Trie) Insert(word string) { | ||
| cur := trie.root | ||
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| for i := 0; i < len(word); i++ { | ||
| if _, ok := cur.next[word[i]]; !ok { | ||
| cur.next[word[i]] = &node{next: make(map[byte]*node)} | ||
| } | ||
| cur, _ = cur.next[word[i]] | ||
| } | ||
| if !cur.isWord { | ||
| cur.isWord = true | ||
| trie.size++ | ||
| } | ||
| } | ||
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| // Search returns if the word is the trie. | ||
| func (trie *Trie) Search(word string) bool { | ||
| cur := trie.root | ||
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| for i := 0; i < len(word); i++ { | ||
| if _, ok := cur.next[word[i]]; !ok { | ||
| return false | ||
| } | ||
| cur, _ = cur.next[word[i]] | ||
| } | ||
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| return cur.isWord | ||
| } | ||
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| // StartsWith returns if there is any word in the trie that starts with the given prefix. | ||
| func (trie *Trie) StartsWith(prefix string) bool { | ||
| cur := trie.root | ||
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| for i := 0; i < len(prefix); i++ { | ||
| if _, ok := cur.next[prefix[i]]; !ok { | ||
| return false | ||
| } | ||
| cur, _ = cur.next[prefix[i]] | ||
| } | ||
| return true | ||
| } |
25 changes: 25 additions & 0 deletions
src/0208_implement_trie_prefix_tree/impltrie_test.go
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,25 @@ | ||
| package impltree | ||
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| import "testing" | ||
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| func TestImplTrie(t *testing.T) { | ||
| trie := Constructor() | ||
| trie.Insert("apple") | ||
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| for i, j := range map[string]bool{"apple": true, "app": false, "hello": false} { | ||
| if res := trie.Search(i); res != j { | ||
| t.Errorf("expected %t, got %t", j, res) | ||
| } | ||
| } | ||
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| for i, j := range map[string]bool{"app": true, "as": false} { | ||
| if res := trie.StartsWith(i); res != j { | ||
| t.Errorf("expected %t, got %t", j, res) | ||
| } | ||
| } | ||
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| trie.Insert("app") | ||
| if res := trie.Search("app"); res != true { | ||
| t.Errorf("expected %t, got %t", true, res) | ||
| } | ||
| } |
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