From a25948107a8b4db03fbe7428d3f1907dcde818b0 Mon Sep 17 00:00:00 2001
From: bona1122 <vnclfjqm12@gmail.com>
Date: Thu, 6 Feb 2025 20:35:27 +0900
Subject: [PATCH 1/7] =?UTF-8?q?Tree=20traversal=20basic=20/=20=EA=B8=B0?=
 =?UTF-8?q?=EC=B4=88?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../Tree_traversal_basic/input.txt            |  8 ++
 .../Tree_traversal_basic/map_version.js       | 50 +++++++++++
 .../node_class_version.js                     | 84 +++++++++++++++++++
 3 files changed, 142 insertions(+)
 create mode 100644 bona1122/[week5]Tree/Tree_traversal_basic/input.txt
 create mode 100644 bona1122/[week5]Tree/Tree_traversal_basic/map_version.js
 create mode 100644 bona1122/[week5]Tree/Tree_traversal_basic/node_class_version.js

diff --git a/bona1122/[week5]Tree/Tree_traversal_basic/input.txt b/bona1122/[week5]Tree/Tree_traversal_basic/input.txt
new file mode 100644
index 0000000..e333156
--- /dev/null
+++ b/bona1122/[week5]Tree/Tree_traversal_basic/input.txt
@@ -0,0 +1,8 @@
+7
+A B C
+B D .
+C E F
+E . .
+F . G
+D . .
+G . .
\ No newline at end of file
diff --git a/bona1122/[week5]Tree/Tree_traversal_basic/map_version.js b/bona1122/[week5]Tree/Tree_traversal_basic/map_version.js
new file mode 100644
index 0000000..3e727f8
--- /dev/null
+++ b/bona1122/[week5]Tree/Tree_traversal_basic/map_version.js
@@ -0,0 +1,50 @@
+const filePath =
+  process.platform === "linux"
+    ? "/dev/stdin"
+    : require("path").join(__dirname, "input.txt")
+const input = require("fs").readFileSync(filePath).toString().trim().split("\n")
+const log = console.log
+
+const N = Number(input[0])
+const tree = new Map()
+
+// 트리 구성
+for (let i = 1; i <= N; i++) {
+  const [node, left, right] = input[i].split(" ")
+  tree.set(node, [left, right])
+}
+
+let result = ""
+
+// 전위 순회
+function preorder(node) {
+  if (node === ".") return
+  result += node // root
+  preorder(tree.get(node)[0]) // left 하위 트리
+  preorder(tree.get(node)[1]) // right 하위 트리
+}
+
+// 중위 순회
+function inorder(node) {
+  if (node === ".") return
+  inorder(tree.get(node)[0]) // left 하위 트리
+  result += node // root
+  inorder(tree.get(node)[1]) // right 하위 트리
+}
+
+// 후위 순회
+function postorder(node) {
+  if (node === ".") return
+  postorder(tree.get(node)[0]) // left 하위 트리
+  postorder(tree.get(node)[1]) // right 하위 트리
+  result += node // root
+}
+
+// 결과 출력
+preorder("A")
+result += "\n"
+inorder("A")
+result += "\n"
+postorder("A")
+
+log(result)
diff --git a/bona1122/[week5]Tree/Tree_traversal_basic/node_class_version.js b/bona1122/[week5]Tree/Tree_traversal_basic/node_class_version.js
new file mode 100644
index 0000000..72eab8a
--- /dev/null
+++ b/bona1122/[week5]Tree/Tree_traversal_basic/node_class_version.js
@@ -0,0 +1,84 @@
+// https://www.acmicpc.net/problem/1991
+// 이진 트리 입력되면, 전위순회/중위순회/후위순회 출력하기
+
+const fs = require("fs")
+const path = require("path")
+const filePath =
+  process.platform === "linux"
+    ? "/dev/stdin"
+    : path.join(__dirname, "input.txt")
+let input = fs.readFileSync(filePath).toString().split("\n")
+const log = console.log
+
+class Node {
+  constructor(value) {
+    this.value = value
+    this.left = null
+    this.right = null
+  }
+}
+
+class BinaryTree {
+  constructor() {
+    this.root = null
+  }
+
+  findNode(value, node = this.root) {
+    if (!node) return null
+    if (node.value === value) return node
+    return this.findNode(value, node.left) || this.findNode(value, node.right)
+  }
+
+  insert(value, left, right) {
+    if (!this.root) {
+      this.root = new Node(value)
+      if (left !== ".") this.root.left = new Node(left)
+      if (right !== ".") this.root.right = new Node(right)
+    } else {
+      const node = this.findNode(value)
+      if (left !== ".") node.left = new Node(left)
+      if (right !== ".") node.right = new Node(right)
+    }
+  }
+}
+
+const N = Number(input[0])
+const tree = new BinaryTree()
+let result = ""
+
+for (let i = 1; i <= N; i++) {
+  const [node, left, right] = input[i].split(" ")
+  tree.insert(node, left, right)
+}
+
+// 전위 순회
+function preorder(node) {
+  if (!node) return
+  result += node.value
+  preorder(node.left)
+  preorder(node.right)
+}
+
+// 중위 순회
+function inorder(node) {
+  if (!node) return
+  inorder(node.left)
+  result += node.value
+  inorder(node.right)
+}
+
+// 후위 순회
+function postorder(node) {
+  if (!node) return
+  postorder(node.left)
+  postorder(node.right)
+  result += node.value
+}
+
+preorder(tree.root)
+result += "\n"
+inorder(tree.root)
+result += "\n"
+postorder(tree.root)
+
+log(result)

From 34c9e3829b03f3909c61b13a5706933777e7d1f7 Mon Sep 17 00:00:00 2001
From: bona1122 <vnclfjqm12@gmail.com>
Date: Thu, 6 Feb 2025 20:36:34 +0900
Subject: [PATCH 2/7] =?UTF-8?q?Complete=20binary=20tree=20/=20=EA=B8=B0?=
 =?UTF-8?q?=EC=B4=88?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../Complete_binary_tree.js                   | 26 +++++++++++++++++++
 .../Complete_binary_tree/input.txt            |  2 ++
 2 files changed, 28 insertions(+)
 create mode 100644 bona1122/[week5]Tree/Complete_binary_tree/Complete_binary_tree.js
 create mode 100644 bona1122/[week5]Tree/Complete_binary_tree/input.txt

diff --git a/bona1122/[week5]Tree/Complete_binary_tree/Complete_binary_tree.js b/bona1122/[week5]Tree/Complete_binary_tree/Complete_binary_tree.js
new file mode 100644
index 0000000..33f22b5
--- /dev/null
+++ b/bona1122/[week5]Tree/Complete_binary_tree/Complete_binary_tree.js
@@ -0,0 +1,26 @@
+// https://www.acmicpc.net/problem/9934
+const filePath =
+  process.platform === "linux"
+    ? "/dev/stdin"
+    : require("path").join(__dirname, "input.txt")
+const input = require("fs").readFileSync(filePath).toString().trim().split("\n")
+const log = console.log
+
+// 상근이는 중위순회로 이진 트리를 순회한 결과를 가지고 있다.
+// 각 레벨에 있는 빌딩 번호 구하기
+const k = +input[0]
+const arr = input[1].split(" ").map(Number)
+let result = Array.from({ length: k }, () => [])
+
+const dfs = (arr, depth) => {
+  if (arr.length < 1) return
+
+  const mid = Math.floor(arr.length / 2)
+  result[depth].push(arr[mid])
+
+  dfs(arr.slice(0, mid), depth + 1)
+  dfs(arr.slice(mid + 1), depth + 1)
+}
+
+dfs(arr, 0)
+result.forEach((row) => log(row.join(" ")))
diff --git a/bona1122/[week5]Tree/Complete_binary_tree/input.txt b/bona1122/[week5]Tree/Complete_binary_tree/input.txt
new file mode 100644
index 0000000..dd601c1
--- /dev/null
+++ b/bona1122/[week5]Tree/Complete_binary_tree/input.txt
@@ -0,0 +1,2 @@
+3
+1 6 4 3 5 2 7
\ No newline at end of file

From 623d66e5b1b8718f7307e344df96a46c97025199 Mon Sep 17 00:00:00 2001
From: bona1122 <vnclfjqm12@gmail.com>
Date: Thu, 6 Feb 2025 20:37:32 +0900
Subject: [PATCH 3/7] =?UTF-8?q?Tree=20find=20parent=20/=20=EA=B8=B0?=
 =?UTF-8?q?=EC=B4=88?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../Tree_find_parent/Tree_find_parent.js      | 36 +++++++++++++++++++
 .../[week5]Tree/Tree_find_parent/input.txt    |  7 ++++
 2 files changed, 43 insertions(+)
 create mode 100644 bona1122/[week5]Tree/Tree_find_parent/Tree_find_parent.js
 create mode 100644 bona1122/[week5]Tree/Tree_find_parent/input.txt

diff --git a/bona1122/[week5]Tree/Tree_find_parent/Tree_find_parent.js b/bona1122/[week5]Tree/Tree_find_parent/Tree_find_parent.js
new file mode 100644
index 0000000..ba0225c
--- /dev/null
+++ b/bona1122/[week5]Tree/Tree_find_parent/Tree_find_parent.js
@@ -0,0 +1,36 @@
+// https://www.acmicpc.net/problem/11725
+
+// 루트없는 트리 주어지면(트리루트 1), 2번노드부터 각 노드의 부모를 구하기
+// => 그래프 정보 저장하고, bfs로 탐색하면서 부모노드 찾기
+const filePath =
+  process.platform === "linux"
+    ? "/dev/stdin"
+    : require("path").join(__dirname, "input.txt")
+const input = require("fs").readFileSync(filePath).toString().trim().split("\n")
+const log = console.log
+
+const n = +input[0]
+const graph = Array.from({ length: n + 1 }, () => [])
+for (let i = 1; i < n; i++) {
+  let [v1, v2] = input[i].split(" ").map(Number)
+  graph[v1].push(v2)
+  graph[v2].push(v1)
+}
+
+const visited = new Array(n + 1).fill(false)
+const parent = new Array(n + 1).fill(0)
+
+const queue = [1]
+visited[1] = true
+
+while (queue.length) {
+  let item = queue.shift()
+
+  for (let v of graph[item]) {
+    if (visited[v]) continue
+    visited[v] = true
+    queue.push(v)
+    parent[v] = item
+  }
+}
+log(result.slice(2).join("\n"))
diff --git a/bona1122/[week5]Tree/Tree_find_parent/input.txt b/bona1122/[week5]Tree/Tree_find_parent/input.txt
new file mode 100644
index 0000000..1387927
--- /dev/null
+++ b/bona1122/[week5]Tree/Tree_find_parent/input.txt
@@ -0,0 +1,7 @@
+7
+1 6
+6 3
+3 5
+4 1
+2 4
+4 7
\ No newline at end of file

From ad58a5f84ce77e6b6c5f80f2764a0a0e07786f34 Mon Sep 17 00:00:00 2001
From: bona1122 <vnclfjqm12@gmail.com>
Date: Thu, 6 Feb 2025 20:38:13 +0900
Subject: [PATCH 4/7] =?UTF-8?q?Binary=5Ftree=5Fheight=20/=20=EA=B8=B0?=
 =?UTF-8?q?=EC=B4=88?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../Binary_tree_height/Binary_tree_height.js  | 50 +++++++++++++++++++
 .../[week5]Tree/Binary_tree_height/input.txt  |  3 ++
 2 files changed, 53 insertions(+)
 create mode 100644 bona1122/[week5]Tree/Binary_tree_height/Binary_tree_height.js
 create mode 100644 bona1122/[week5]Tree/Binary_tree_height/input.txt

diff --git a/bona1122/[week5]Tree/Binary_tree_height/Binary_tree_height.js b/bona1122/[week5]Tree/Binary_tree_height/Binary_tree_height.js
new file mode 100644
index 0000000..72dca4b
--- /dev/null
+++ b/bona1122/[week5]Tree/Binary_tree_height/Binary_tree_height.js
@@ -0,0 +1,50 @@
+// https://www.acmicpc.net/problem/1068
+const filePath =
+  process.platform === "linux"
+    ? "/dev/stdin"
+    : require("path").join(__dirname, "input.txt")
+const input = require("fs").readFileSync(filePath).toString().trim().split("\n")
+const log = console.log
+
+// 노드 제거시, 노드와 노드의 모든 자손이 트리에서 제거됨
+// 노드를 지운 후, 트리의 리프노드 개수 구하기
+// => 부모노드 정보를 통해 그래프를 구성하고, bfs로 탐색하며 리프노드 개수 카운트
+
+const n = +input[0]
+const parents = input[1].split(" ").map(Number)
+const remove = +input[2]
+const graph = Array.from({ length: n }, () => [])
+let root = -1
+
+for (let i = 0; i < n; i++) {
+  const parent = parents[i]
+  if (parent === -1) {
+    root = i
+  } else {
+    graph[parent].push(i)
+  }
+}
+
+let result = 0
+const queue = remove === root ? [] : [root]
+const visited = new Array(n).fill(false)
+visited[root] = true
+
+while (queue.length) {
+  let item = queue.shift()
+  let isLeaf = true
+
+  for (let v of graph[item]) {
+    if (v !== remove) {
+      isLeaf = false
+      if (!visited[v]) {
+        visited[v] = true
+        queue.push(v)
+      }
+    }
+  }
+
+  if (isLeaf) result++
+}
+
+log(result)
diff --git a/bona1122/[week5]Tree/Binary_tree_height/input.txt b/bona1122/[week5]Tree/Binary_tree_height/input.txt
new file mode 100644
index 0000000..399e5c8
--- /dev/null
+++ b/bona1122/[week5]Tree/Binary_tree_height/input.txt
@@ -0,0 +1,3 @@
+9
+-1 0 0 2 2 4 4 6 6
+4
\ No newline at end of file

From e09fbed67a992fa0c51d6cf73838e7d41dad5cf5 Mon Sep 17 00:00:00 2001
From: bona1122 <vnclfjqm12@gmail.com>
Date: Thu, 6 Feb 2025 20:39:13 +0900
Subject: [PATCH 5/7] =?UTF-8?q?Binary=20search=20tree=20/=20=EC=A4=91?=
 =?UTF-8?q?=EA=B8=89?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../Binary_search_tree/Binary_search_tree.js  | 29 +++++++++
 .../Binary_search_tree_class_version.js       | 62 +++++++++++++++++++
 .../[week5]Tree/Binary_search_tree/input.txt  |  9 +++
 3 files changed, 100 insertions(+)
 create mode 100644 bona1122/[week5]Tree/Binary_search_tree/Binary_search_tree.js
 create mode 100644 bona1122/[week5]Tree/Binary_search_tree/Binary_search_tree_class_version.js
 create mode 100644 bona1122/[week5]Tree/Binary_search_tree/input.txt

diff --git a/bona1122/[week5]Tree/Binary_search_tree/Binary_search_tree.js b/bona1122/[week5]Tree/Binary_search_tree/Binary_search_tree.js
new file mode 100644
index 0000000..9f30847
--- /dev/null
+++ b/bona1122/[week5]Tree/Binary_search_tree/Binary_search_tree.js
@@ -0,0 +1,29 @@
+// https://www.acmicpc.net/problem/5639
+// 이진 검색트리의 전위 순회 경과가 주어지면, 후위순회 결과 구하기
+const filePath =
+  process.platform === "linux"
+    ? "/dev/stdin"
+    : require("path").join(__dirname, "input.txt")
+const input = require("fs").readFileSync(filePath).toString().trim().split("\n")
+const log = console.log
+
+const arr = input.map(Number)
+
+const postorder = (root, end) => {
+  if (root > end) return
+
+  let right = end + 1 // 오른쪽 서브트리(루트보다 큰 요소들) 시작점 구하기
+  for (let i = root + 1; i <= end; i++) {
+    if (arr[i] > arr[root]) {
+      right = i
+      break
+    }
+  }
+
+  // 후위 순위로 출력
+  postorder(root + 1, right - 1)
+  postorder(right, end)
+  log(arr[root])
+}
+
+postorder(0, arr.length - 1)
diff --git a/bona1122/[week5]Tree/Binary_search_tree/Binary_search_tree_class_version.js b/bona1122/[week5]Tree/Binary_search_tree/Binary_search_tree_class_version.js
new file mode 100644
index 0000000..8dd5205
--- /dev/null
+++ b/bona1122/[week5]Tree/Binary_search_tree/Binary_search_tree_class_version.js
@@ -0,0 +1,62 @@
+// https://www.acmicpc.net/problem/5639
+// 이진 검색트리의 전위 순회 경과가 주어지면, 후위순회 결과 구하기
+
+// 핵심: BST의 전위순회 결과가 있기에, 순서대로 트리에 삽입하면 트리가 복원된다
+const filePath =
+  process.platform === "linux"
+    ? "/dev/stdin"
+    : require("path").join(__dirname, "input.txt")
+const input = require("fs").readFileSync(filePath).toString().trim().split("\n")
+const log = console.log
+
+const arr = input.map(Number)
+
+class Node {
+  constructor(value) {
+    this.value = value
+    this.left = null
+    this.right = null
+  }
+}
+
+class BinarySearchTree {
+  constructor() {
+    this.root = null
+  }
+
+  insert(value) {
+    if (!this.root) {
+      this.root = new Node(value)
+      return
+    }
+
+    let current = this.root
+    while (true) {
+      if (value < current.value) {
+        if (!current.left) {
+          current.left = new Node(value)
+          break
+        }
+        current = current.left
+      } else {
+        if (!current.right) {
+          current.right = new Node(value)
+          break
+        }
+        current = current.right
+      }
+    }
+  }
+
+  postorder(node = this.root) {
+    if (!node) return
+
+    this.postorder(node.left) // 왼쪽 서브트리 순회
+    this.postorder(node.right) // 오른쪽 서브트리 순회
+    log(node.value) // 현재 노드 출력
+  }
+}
+
+const tree = new BinarySearchTree()
+arr.forEach((item) => tree.insert(item))
+tree.postorder()
diff --git a/bona1122/[week5]Tree/Binary_search_tree/input.txt b/bona1122/[week5]Tree/Binary_search_tree/input.txt
new file mode 100644
index 0000000..e5d3e90
--- /dev/null
+++ b/bona1122/[week5]Tree/Binary_search_tree/input.txt
@@ -0,0 +1,9 @@
+50
+30
+24
+5
+28
+45
+98
+52
+60
\ No newline at end of file

From bd92ea1081b2e39eb16df1e8927de80ef8969725 Mon Sep 17 00:00:00 2001
From: bona1122 <vnclfjqm12@gmail.com>
Date: Thu, 6 Feb 2025 20:39:56 +0900
Subject: [PATCH 6/7] =?UTF-8?q?Tree=20and=20query=20/=20=EC=A4=91=EA=B8=89?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../Tree_and_query/Tree_and_query.js          | 68 +++++++++++++++++++
 bona1122/[week5]Tree/Tree_and_query/input.txt | 12 ++++
 2 files changed, 80 insertions(+)
 create mode 100644 bona1122/[week5]Tree/Tree_and_query/Tree_and_query.js
 create mode 100644 bona1122/[week5]Tree/Tree_and_query/input.txt

diff --git a/bona1122/[week5]Tree/Tree_and_query/Tree_and_query.js b/bona1122/[week5]Tree/Tree_and_query/Tree_and_query.js
new file mode 100644
index 0000000..3a0a69f
--- /dev/null
+++ b/bona1122/[week5]Tree/Tree_and_query/Tree_and_query.js
@@ -0,0 +1,68 @@
+// https://www.acmicpc.net/problem/15681
+const filePath =
+  process.platform === "linux"
+    ? "/dev/stdin"
+    : require("path").join(__dirname, "input.txt")
+const input = require("fs").readFileSync(filePath).toString().trim().split("\n")
+const log = console.log
+
+// 가중치, 방향 없는 트리
+// 정점 U를 루트로 하는 서브트리에 속한 정점 수 출력하기
+
+// 방법 1: 문제에서 주어진 힌트 처럼, 자식 배열을 활용
+const [N, R, Q] = input[0].split(" ").map(Number)
+
+const graph = Array.from({ length: N + 1 }, () => [])
+const query = Array(Q)
+const children = Array.from({ length: N + 1 }, () => [])
+const size = Array(N + 1).fill(1)
+
+for (let i = 1; i <= N - 1; i++) {
+  let [u, v] = input[i].split(" ").map(Number)
+  graph[u].push(v)
+  graph[v].push(u)
+}
+let idx = 0
+for (let i = N; i < N + Q; i++) {
+  query[idx++] = +input[i]
+}
+
+const makeTree = (cur, parent) => {
+  for (let next of graph[cur]) {
+    if (next !== parent) {
+      children[cur].push(next)
+      makeTree(next, cur)
+    }
+  }
+}
+
+// 부모자식관계를 파악하기 위한 두 가지 방법
+// 1. 명시적으로 배열에 저장 -> makeTree 선행 필요
+const countSubtreeNodes = (cur) => {
+  for (let next of children[cur]) {
+    countSubtreeNodes(next)
+    size[cur] += size[next]
+  }
+}
+// 2. visited배열로 부모자식 파악
+const visited = Array(N + 1).fill(false)
+const countSubtreeNodes2 = (node) => {
+  if (visited[node]) return size[node]
+  visited[node] = true // 방문 표시로 부모-자식 관계 파악
+
+  for (const next of graph[node]) {
+    if (!visited[next]) {
+      // 방문하지 않은 노드는 자식
+      size[node] += countSubtreeNodes2(next)
+    }
+  }
+  return size[node]
+}
+/*
+ makeTree(R, 0)
+ countSubtreeNodes(R)
+ log(children)
+*/
+countSubtreeNodes2(R)
+
+for (let q of query) log(size[q])
diff --git a/bona1122/[week5]Tree/Tree_and_query/input.txt b/bona1122/[week5]Tree/Tree_and_query/input.txt
new file mode 100644
index 0000000..94052f7
--- /dev/null
+++ b/bona1122/[week5]Tree/Tree_and_query/input.txt
@@ -0,0 +1,12 @@
+9 5 3
+1 3
+4 3
+5 4
+5 6
+6 7
+2 3
+9 6
+6 8
+5
+4
+8
\ No newline at end of file

From fa5494b49104bd54569cfbb613c3760fac13d8b2 Mon Sep 17 00:00:00 2001
From: bona1122 <vnclfjqm12@gmail.com>
Date: Thu, 6 Feb 2025 20:40:43 +0900
Subject: [PATCH 7/7] =?UTF-8?q?Tree=5Ftraversal=20/=20=EC=8B=AC=ED=99=94?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../Tree_traversal/Tree_traversal.js          | 40 +++++++++++++++++++
 bona1122/[week5]Tree/Tree_traversal/input.txt |  3 ++
 2 files changed, 43 insertions(+)
 create mode 100644 bona1122/[week5]Tree/Tree_traversal/Tree_traversal.js
 create mode 100644 bona1122/[week5]Tree/Tree_traversal/input.txt

diff --git a/bona1122/[week5]Tree/Tree_traversal/Tree_traversal.js b/bona1122/[week5]Tree/Tree_traversal/Tree_traversal.js
new file mode 100644
index 0000000..90cd98d
--- /dev/null
+++ b/bona1122/[week5]Tree/Tree_traversal/Tree_traversal.js
@@ -0,0 +1,40 @@
+// https://www.acmicpc.net/problem/2263
+const filePath =
+  process.platform === "linux"
+    ? "/dev/stdin"
+    : require("path").join(__dirname, "input.txt")
+const input = require("fs").readFileSync(filePath).toString().trim().split("\n")
+const log = console.log
+
+// n개의 정점존재, 이진트리의 inorder, postorder 주어지면, preorder 구하기
+const n = +input[0]
+const inorder = input[1].split(" ").map(Number)
+const postorder = input[2].split(" ").map(Number)
+let result = ""
+
+// 매번 findIndex하니, 시간초과가 남. => inorder 값의 인덱스를 미리 Map에 저장해두기
+const inorderMap = new Map()
+inorder.forEach((val, idx) => inorderMap.set(val, idx))
+
+// postorder로 루트 알아내고,
+// 그 정보를 통해 inorder에서 왼/오 서브트리 알아내기
+// iStart, iEnd: inorder 배열의 범위
+// pStart, pEnd: postorder 배열의 범위
+const preorder = (iStart, iEnd, pStart, pEnd) => {
+  if (iStart > iEnd || pStart > pEnd) return
+
+  const root = postorder[pEnd]
+  const rootIdx = inorderMap.get(root)
+  result += `${root} `
+
+  const leftSize = rootIdx - iStart // 왼쪽 서브트리 크기
+
+  // 왼쪽 서브트리 처리
+  preorder(iStart, rootIdx - 1, pStart, pStart + leftSize - 1)
+
+  // 오른쪽 서브트리 처리
+  preorder(rootIdx + 1, iEnd, pStart + leftSize, pEnd - 1)
+}
+
+preorder(0, n - 1, 0, n - 1)
+log(result.trim())
diff --git a/bona1122/[week5]Tree/Tree_traversal/input.txt b/bona1122/[week5]Tree/Tree_traversal/input.txt
new file mode 100644
index 0000000..e3fe03c
--- /dev/null
+++ b/bona1122/[week5]Tree/Tree_traversal/input.txt
@@ -0,0 +1,3 @@
+3
+1 2 3
+1 3 2
\ No newline at end of file