[Tree] baekjoon-2263

Author: Seogeurim

README.md

@@ -154,6 +154,7 @@
 | 02  |     | [Baekjoon-1068 트리](./src/Tree/P1068)       |      |
 | 03  |     | [SWEA-1233 사칙연산 유효성 검사](./src/Tree/swea1233) |      |
 | 04  | ⭐️ | [Baekjoon-1167 트리의 지름](./src/Tree/P1167)   |      |
+| 05  | ⭐️ | [Baekjoon-2263 트리의 순회](./src/Tree/P2263)   |      |
 
 ### Heap
 

src/Tree/P2263/Main.java

@@ -0,0 +1,41 @@
+package Tree.P2263;
+
+import java.io.*;
+import java.util.StringTokenizer;
+
+public class Main {
+
+    static int n;
+    static int[] in, post;
+    static StringBuilder sb = new StringBuilder();
+
+    public static void main(String[] args) throws Exception {
+        System.setIn(new FileInputStream("src/Tree/P2263/input.txt"));
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        n = Integer.parseInt(br.readLine());
+        in = new int[n];
+        post = new int[n];
+
+        StringTokenizer st1 = new StringTokenizer(br.readLine());
+        StringTokenizer st2 = new StringTokenizer(br.readLine());
+        for (int i = 0; i < n; i++) {
+            in[i] = Integer.parseInt(st1.nextToken());
+            post[i] = Integer.parseInt(st2.nextToken());
+        }
+
+        search(0, n-1, 0, n-1);
+        System.out.println(sb.toString());
+    }
+
+    static void search(int i_s, int i_e, int p_s, int p_e) {
+        int root = post[p_e], mid;
+        sb.append(root).append(" ");
+        if (i_s == i_e) return;
+        for (mid = i_s; mid <= i_e; mid++) {
+            if (in[mid] == root) break;
+        }
+        if (i_s <= mid-1) search(i_s, mid-1, p_s, p_s+(mid-i_s)-1);
+        if (mid < i_e) search(mid+1, i_e, p_s+(mid-i_s), p_e-1);
+    }
+}

src/Tree/P2263/README.md

@@ -0,0 +1,12 @@
+## [baekjoon-2263] 트리의 순회
+
+![image](https://user-images.githubusercontent.com/22045163/108312939-c3763a00-71fa-11eb-8836-289469ba1438.png)
+
+### 풀이 과정
+
+- postorder의 가장 오른쪽은 부모 노드
+- inorder는 부모 노드를 중간에 두고 좌, 우로 자식 노드를 가짐
+
+![image](https://user-images.githubusercontent.com/22045163/108312825-a3df1180-71fa-11eb-9c10-dd790fa2602d.png)
+
+![image](https://user-images.githubusercontent.com/22045163/108312955-cec96580-71fa-11eb-868f-6e6e993ddc9e.png)

src/Tree/P2263/input.txt

@@ -0,0 +1,13 @@
+7
+4 2 1 5 3 6 7
+4 2 5 7 6 3 1
+//1243567
+
+7
+6 2 5 3 1 4 7
+6 5 2 1 7 4 3
+//3265417
+
+3
+1 2 3
+1 3 2