[20250714] BOJ / G1 / 트리의 순회 / 이강현

lkhyun/202507/14 BOJ G1 트리의 순회.md

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+```java
+import java.util.*;
+import java.io.*;
+
+public class Main{
+    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    static StringTokenizer st;
+    static int N;
+    static int[] inOrder;
+    static int[] postOrder;
+    static int[] findInOrderIdxByValue;
+
+    static int[] preOrder;
+    static int preOrderIdx = 1;
+
+    public static void main(String[] args) throws Exception{
+        N = Integer.parseInt(br.readLine());
+        inOrder = new int[N+1];
+        postOrder = new int[N+1];
+        findInOrderIdxByValue = new int[N+1];
+        preOrder = new int[N+1];
+
+        st = new StringTokenizer(br.readLine());
+        for (int i = 1; i <= N; i++) {
+            inOrder[i] = Integer.parseInt(st.nextToken());
+            findInOrderIdxByValue[inOrder[i]] = i;
+        }
+        st = new StringTokenizer(br.readLine());
+        for (int i = 1; i <= N; i++) {
+            postOrder[i] = Integer.parseInt(st.nextToken());
+        }
+        search(1,N,1,N);
+        for (int i = 1; i <= N; i++) {
+            bw.write(preOrder[i]+" ");
+        }
+        bw.close();
+    }
+    static void search(int InStart, int InEnd, int PostStart, int PostEnd){
+        if(PostStart > PostEnd) return;
+        int rootIdx = findInOrderIdxByValue[postOrder[PostEnd]];
+        preOrder[preOrderIdx++] = postOrder[PostEnd];
+        int leftSize = rootIdx - InStart;
+        int rightSize = InEnd - rootIdx;
+
+        search(InStart, rootIdx-1,PostStart,PostStart+leftSize-1);
+        search(rootIdx+1, InEnd, PostEnd-rightSize, PostEnd-1);
+    }
+}
+```