feat(0208): Implement Trie (Prefix Tree)

Author: zangbianxuegu

0208. Implement Trie (Prefix Tree).js

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+// Implement a trie with insert, search, and startsWith methods.
+
+// Example:
+
+// Trie trie = new Trie();
+
+// trie.insert("apple");
+// trie.search("apple");   // returns true
+// trie.search("app");     // returns false
+// trie.startsWith("app"); // returns true
+// trie.insert("app");   
+// trie.search("app");     // returns true
+// Note:
+
+// You may assume that all inputs are consist of lowercase letters a-z.
+// All inputs are guaranteed to be non-empty strings.
+
+
+// 1)
+// 做完之后看 Discuss，没太明白为啥都是那种复杂的。
+class Trie {
+  constructor () {
+    this.list = []
+  }
+  insert (word) {
+    this.list.push(word)
+  }
+  search (word) {
+    return this.list.indexOf(word) > -1
+  }
+  startsWith (prefix) {  
+    let res = false  
+    this.list.forEach(word => {      
+      if (word.indexOf(prefix) === 0) {
+        res = true
+      }
+    })
+    return res
+  }
+}
+// Runtime: 492 ms, faster than 6.10% of JavaScript online submissions for Implement Trie (Prefix Tree).
+// Memory Usage: 47.7 MB, less than 99.88% of JavaScript online submissions for Implement Trie (Prefix Tree).