feat: Lv4 가사 검색 풀이 추가

Author: ryong9rrr

level-4/가사-검색.js

@@ -0,0 +1,73 @@
+//https://github.com/codeisneverodd/programmers-coding-test
+//더 좋은 풀이가 존재할 수 있습니다.
+//정답 1 - ryong9rrr
+class Node {
+  constructor(value = '') {
+    this.value = value
+    this.children = new Map()
+    this.count = 0
+  }
+}
+
+class Trie {
+  constructor() {
+    this.root = new Node()
+  }
+
+  insert(string) {
+    let currentNode = this.root
+    for (const char of string) {
+      if (!currentNode.children.has(char)) {
+        currentNode.children.set(char, new Node(currentNode.value + char))
+      }
+      currentNode = currentNode.children.get(char)
+      currentNode.count++
+    }
+  }
+
+  startsWithCount(prefix) {
+    let currentNode = this.root
+    for (const char of prefix) {
+      if (!currentNode.children.has(char)) {
+        return 0
+      }
+      currentNode = currentNode.children.get(char)
+    }
+    return currentNode.count
+  }
+}
+
+function reverseString(string) {
+  return [...string].reverse().join('')
+}
+
+function solution(words, queries) {
+  const table = {}
+  const reverseTable = {}
+  const counter = {}
+
+  words.forEach((word) => {
+    const key = word.length
+    if (!table[key]) table[key] = new Trie()
+    if (!reverseTable[key]) reverseTable[key] = new Trie()
+    table[key].insert(word)
+    reverseTable[key].insert(reverseString(word))
+    if (counter[key] === undefined) counter[key] = 0
+    counter[key]++
+  })
+
+  return queries.map((query) => {
+    const key = query.length
+    if (!table[key]) {
+      return 0
+    }
+    const tQuery = query.replace(/\?/g, '')
+    if (!tQuery) {
+      return counter[key]
+    }
+    if (query[query.length - 1] === '?') {
+      return table[key].startsWithCount(tQuery)
+    }
+    return reverseTable[key].startsWithCount(reverseString(tQuery))
+  })
+}