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99 lines
2.2 KiB
Markdown
Executable File
99 lines
2.2 KiB
Markdown
Executable File
# [208. Implement Trie (Prefix Tree)](https://leetcode.com/problems/implement-trie-prefix-tree/)
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## 题目
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Implement a trie with `insert`, `search`, and `startsWith` methods.
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**Example**:
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Trie trie = new Trie();
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trie.insert("apple");
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trie.search("apple"); // returns true
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trie.search("app"); // returns false
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trie.startsWith("app"); // returns true
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trie.insert("app");
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trie.search("app"); // returns true
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**Note**:
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- You may assume that all inputs are consist of lowercase letters `a-z`.
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- All inputs are guaranteed to be non-empty strings.
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## 题目大意
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实现一个 Trie (前缀树)，包含 insert, search, 和 startsWith 这三个操作。
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## 解题思路
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- 要求实现一个 Trie 的数据结构，具有 `insert`, `search`, `startsWith` 三种操作
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- 这一题就是经典的 Trie 实现。本题的实现可以作为 Trie 的模板。
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## 代码
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```go
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package leetcode
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type Trie struct {
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isWord bool
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children map[rune]*Trie
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}
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/** Initialize your data structure here. */
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func Constructor208() Trie {
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return Trie{isWord: false, children: make(map[rune]*Trie)}
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}
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/** Inserts a word into the trie. */
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func (this *Trie) Insert(word string) {
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parent := this
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for _, ch := range word {
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if child, ok := parent.children[ch]; ok {
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parent = child
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} else {
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newChild := &Trie{children: make(map[rune]*Trie)}
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parent.children[ch] = newChild
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parent = newChild
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}
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}
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parent.isWord = true
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}
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/** Returns if the word is in the trie. */
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func (this *Trie) Search(word string) bool {
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parent := this
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for _, ch := range word {
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if child, ok := parent.children[ch]; ok {
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parent = child
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continue
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}
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return false
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}
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return parent.isWord
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}
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/** Returns if there is any word in the trie that starts with the given prefix. */
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func (this *Trie) StartsWith(prefix string) bool {
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parent := this
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for _, ch := range prefix {
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if child, ok := parent.children[ch]; ok {
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parent = child
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continue
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}
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return false
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}
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return true
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}
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/**
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* Your Trie object will be instantiated and called as such:
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* obj := Constructor();
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* obj.Insert(word);
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* param_2 := obj.Search(word);
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* param_3 := obj.StartsWith(prefix);
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*/
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``` |