From dff4d18e156a65dff1730dac210e0cf2ffae01f2 Mon Sep 17 00:00:00 2001
From: zinnnn37 <zinnnn37@gmail.com>
Date: Mon, 8 Dec 2025 23:26:33 +0900
Subject: [PATCH] =?UTF-8?q?[20251208]=20BOJ=20/=20G4=20/=20=EA=B2=8C?=
 =?UTF-8?q?=EC=9E=84=20/=20=EA=B9=80=EB=AF=BC=EC=A7=84?=
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---
 .../8 BOJ G4 \352\262\214\354\236\204.md"     | 78 +++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 "zinnnn37/202512/8 BOJ G4 \352\262\214\354\236\204.md"

diff --git "a/zinnnn37/202512/8 BOJ G4 \352\262\214\354\236\204.md" "b/zinnnn37/202512/8 BOJ G4 \352\262\214\354\236\204.md"
new file mode 100644
index 00000000..c59ed6c6
--- /dev/null
+++ "b/zinnnn37/202512/8 BOJ G4 \352\262\214\354\236\204.md"	
@@ -0,0 +1,78 @@
+```java
+import java.io.*;
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+public class BJ_28423_게임 {
+
+    private static final BufferedReader  br = new BufferedReader(new InputStreamReader(System.in));
+    private static final BufferedWriter  bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    private static       StringTokenizer st;
+
+    private static int L, R, ans;
+    private static int[]     memo;
+    private static boolean[] checked;
+
+    public static void main(String[] args) throws IOException {
+        init();
+        sol();
+    }
+
+    private static void init() throws IOException {
+        st = new StringTokenizer(br.readLine());
+        L = Integer.parseInt(st.nextToken());
+        R = Integer.parseInt(st.nextToken());
+
+        ans = 0;
+        memo = new int[100_001];
+        checked = new boolean[100_001];
+        Arrays.fill(memo, 2);
+    }
+
+    private static void sol() throws IOException {
+        for (int i = L; i <= R; i++) {
+            ans += dfs(i);
+        }
+        bw.write(ans + "");
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static int dfs(int cur) {
+        if (memo[cur] != 2) {
+            return memo[cur];
+        }
+
+        if (checked[cur]) {
+            return memo[cur] = 0;
+        }
+
+        checked[cur] = true;
+
+        int A = 0;
+        int B = 1;
+
+        int tmp = cur;
+        while (tmp != 0) {
+            A += tmp % 10;
+            B *= tmp % 10;
+            tmp /= 10;
+        }
+
+        int res = Integer.parseInt(String.valueOf(A) + String.valueOf(B));
+
+        if (cur == res) {
+            memo[cur] = 1;
+        } else if (res > 100000) {
+            memo[cur] = -1;
+        } else {
+            memo[cur] = dfs(res);
+        }
+        checked[cur] = false;
+
+        return memo[cur];
+    }
+
+}
+```
\ No newline at end of file