Merge pull request #909 from AlgorithmWithGod/JHLEE325

[20250917] BOJ / G4 / DSLR/ 이준희

Author: ShinHeeEul

JHLEE325/202509/17 BOJ G4 DSLR.md

@@ -0,0 +1,85 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static class Node {
+        int num;
+        String cmd;
+
+        Node(int num, String cmd) {
+            this.num = num;
+            this.cmd = cmd;
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringBuilder sb = new StringBuilder();
+        int T = Integer.parseInt(br.readLine());
+
+        for (int t = 0; t < T; t++) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            int A = Integer.parseInt(st.nextToken());
+            int B = Integer.parseInt(st.nextToken());
+
+            boolean[] visited = new boolean[10000];
+            Queue<Node> q = new ArrayDeque<>();
+
+            q.add(new Node(A, ""));
+            visited[A] = true;
+
+            while (!q.isEmpty()) {
+                Node cur = q.poll();
+
+                if (cur.num == B) {
+                    sb.append(cur.cmd).append("\n");
+                    break;
+                }
+
+                int d = D(cur.num);
+                if (!visited[d]) {
+                    visited[d] = true;
+                    q.add(new Node(d, cur.cmd + "D"));
+                }
+
+                int s = S(cur.num);
+                if (!visited[s]) {
+                    visited[s] = true;
+                    q.add(new Node(s, cur.cmd + "S"));
+                }
+
+                int l = L(cur.num);
+                if (!visited[l]) {
+                    visited[l] = true;
+                    q.add(new Node(l, cur.cmd + "L"));
+                }
+
+                int r = R(cur.num);
+                if (!visited[r]) {
+                    visited[r] = true;
+                    q.add(new Node(r, cur.cmd + "R"));
+                }
+            }
+        }
+        System.out.print(sb);
+    }
+
+    static int D(int n) {
+        return (2 * n) % 10000;
+    }
+
+    static int S(int n) {
+        return (n == 0) ? 9999 : n - 1;
+    }
+
+    static int L(int n) {
+        return (n % 1000) * 10 + n / 1000;
+    }
+
+    static int R(int n) {
+        return (n / 10) + (n % 10) * 1000;
+    }
+}
+```