feat: implement trie prefix tree

Author: anniemon

implement-trie-prefix-tree/anniemon.js

@@ -0,0 +1,61 @@
+/**
+ * 시간 복잡도: 주어진 문자열의 길이만큼 순회하므로, O(n)
+ * 공간 복잡도: 삽입된 모든 문자열의 길이만큼 노드가 만들어지므로, 이를 m이라고 하면 O(m)
+ */
+var Trie = function() {
+  this.isEnd = false;
+  this.children = {};
+};
+
+/** 
+* @param {string} word
+* @return {void}
+*/
+Trie.prototype.insert = function(word) {
+  let cur = this.children;
+  for(const c of word) {
+      if(!cur[c]) {
+          cur[c] = { isEnd: false, children: {} };
+      }
+      cur = cur[c];
+  }
+  cur.isEnd = true;
+};
+
+/** 
+* @param {string} word
+* @return {boolean}
+*/
+Trie.prototype.search = function(word) {
+  let cur = this.children;
+  for(const c of word) {
+      if(!cur[c]) {
+          return false;
+      }
+      cur = cur[c]
+  }
+  return cur.isEnd;
+};
+
+/** 
+* @param {string} prefix
+* @return {boolean}
+*/
+Trie.prototype.startsWith = function(prefix) {
+  let cur = this.children;
+  for(const c of prefix) {
+      if(!cur[c]){
+          return false;
+      }
+      cur = cur[c];
+  }
+  return true;
+};
+
+/**
+* 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)
+*/