字典树: 系统设计

Change-Id: I96eedfe461b87158272b7023d58a0e229a4d7168

Author: qieguo2016

go/leetcode/208.实现-trie-前缀树.go

@@ -0,0 +1,104 @@
+package leetcode
+
+/*
+ * @lc app=leetcode.cn id=208 lang=golang
+ *
+ * [208] 实现 Trie (前缀树)
+ *
+ * https://leetcode-cn.com/problems/implement-trie-prefix-tree/description/
+ *
+ * algorithms
+ * Medium (61.14%)
+ * Likes:    129
+ * Dislikes: 0
+ * Total Accepted:    13.4K
+ * Total Submissions: 21.8K
+ * Testcase Example:  '["Trie","insert","search","search","startsWith","insert","search"]\n[[],["apple"],["apple"],["app"],["app"],["app"],["app"]]'
+ *
+ * 实现一个 Trie (前缀树)，包含 insert, search, 和 startsWith 这三个操作。
+ *
+ * 示例:
+ *
+ * Trie trie = new Trie();
+ *
+ * trie.insert("apple");
+ * trie.search("apple");   // 返回 true
+ * trie.search("app");     // 返回 false
+ * trie.startsWith("app"); // 返回 true
+ * trie.insert("app");
+ * trie.search("app");     // 返回 true
+ *
+ * 说明:
+ *
+ *
+ * 你可以假设所有的输入都是由小写字母 a-z 构成的。
+ * 保证所有输入均为非空字符串。
+ *
+ *
+ */
+
+// @lc code=start
+type Node struct {
+	Child map[rune]*Node
+	Value bool
+}
+
+type Trie struct {
+	Root *Node
+}
+
+/** Initialize your data structure here. */
+func Constructor() Trie {
+	return Trie{
+		Root: &Node{
+			Child: map[rune]*Node{},
+		},
+	}
+}
+
+/** Inserts a word into the trie. */
+func (this *Trie) Insert(word string) {
+	cur := this.Root
+	for _, c := range word {
+		if _, ok := cur.Child[c]; !ok {
+			cur.Child[c] = &Node{
+				Child: map[rune]*Node{},
+			}
+		}
+		cur = cur.Child[c]
+	}
+	cur.Value = true
+}
+
+/** Returns if the word is in the trie. */
+func (this *Trie) Search(word string) bool {
+	cur := this.Root
+	for _, c := range word {
+		if _, ok := cur.Child[c]; !ok {
+			return false
+		}
+		cur = cur.Child[c]
+	}
+	return cur.Value
+}
+
+/** Returns if there is any word in the trie that starts with the given prefix. */
+func (this *Trie) StartsWith(prefix string) bool {
+	cur := this.Root
+	for _, c := range prefix {
+		if _, ok := cur.Child[c]; !ok {
+			return false
+		}
+		cur = cur.Child[c]
+	}
+	return true
+}
+
+/**
+ * Your Trie object will be instantiated and called as such:
+ * obj := Constructor();
+ * obj.Insert(word);
+ * param_2 := obj.Search(word);
+ * param_3 := obj.StartsWith(prefix);
+ */
+// @lc code=end