leetcode: 前缀树

Author: Z1hgq

daily-leetcode/prefixTree.js

@@ -0,0 +1,76 @@
+/**
+ * 前缀树
+ * https://leetcode-cn.com/problems/implement-trie-prefix-tree/
+/**
+ * Initialize your data structure here.
+ */
+ var Trie = function () {
+    this.value = '';
+    this.isWord = false;
+    this.children = new Array(26);
+};
+
+/**
+ * Inserts a word into the trie. 
+ * @param {string} word
+ * @return {void}
+ */
+Trie.prototype.insert = function (word) {
+    let curLetter = this;
+    for (let i = 0; i < word.length; i++) {
+        const index = word[i].charCodeAt() - 'a'.charCodeAt();
+        if (!curLetter.children[index]) {
+            curLetter.children[index] = new Trie();
+            curLetter.children[index].value = word[i];
+        }
+        curLetter = curLetter.children[index];
+    }
+    curLetter.isWord = true;
+};
+
+/**
+ * Returns if the word is in the trie. 
+ * @param {string} word
+ * @return {boolean}
+ */
+Trie.prototype.search = function (word) {
+    return this.find(word).flag && this.find(word).curLetter.isWord;
+};
+
+/**
+ * Returns if there is any word in the trie that starts with the given prefix. 
+ * @param {string} prefix
+ * @return {boolean}
+ */
+Trie.prototype.startsWith = function (prefix) {
+    return this.find(prefix).flag;
+};
+
+Trie.prototype.find = function (prefix) {
+    let curLetter = this;
+    let flag = true;
+    for (let i = 0; i < prefix.length; i++) {
+        const index = prefix[i].charCodeAt() - 'a'.charCodeAt();
+        if (curLetter.children[index]) {
+            curLetter = curLetter.children[index];
+            continue;
+        }
+        flag = false;
+        break;
+    }
+    return { flag, curLetter };
+}
+
+/**
+ * Your Trie object will be instantiated and called as such:
+ * var obj = new Trie()
+ * obj.insert(word)
+ * var param_2 = obj.search(word)
+ * var param_3 = obj.startsWith(prefix)
+ */
+var obj = new Trie()
+obj.insert('apple')
+var param_2 = obj.search('app')
+var param_3 = obj.startsWith('app')
+
+console.log(obj, param_2, param_3);