From a726d75de1c071e388f1f971d5a4e5788e396dde Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EA=B0=95=EC=8B=A0=EC=A7=80?=
 <101992179+ksinji@users.noreply.github.com>
Date: Fri, 21 Nov 2025 20:02:53 +0900
Subject: [PATCH] =?UTF-8?q?[20251121]=20BOJ=20/=20G5=20/=20=EB=B9=97?=
 =?UTF-8?q?=EB=AC=BC=20/=20=EA=B0=95=EC=8B=A0=EC=A7=80?=
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---
 .../21 BOJ \353\271\227\353\254\274.md"       | 35 +++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 "ksinji/202511/21 BOJ \353\271\227\353\254\274.md"

diff --git "a/ksinji/202511/21 BOJ \353\271\227\353\254\274.md" "b/ksinji/202511/21 BOJ \353\271\227\353\254\274.md"
new file mode 100644
index 00000000..0bb8fc07
--- /dev/null
+++ "b/ksinji/202511/21 BOJ \353\271\227\353\254\274.md"	
@@ -0,0 +1,35 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        int h = Integer.parseInt(st.nextToken());
+        int w = Integer.parseInt(st.nextToken());
+
+        int[] height = new int[w];
+
+        st = new StringTokenizer(br.readLine());
+        for (int i=0; i<w; i++){
+            height[i] = Integer.parseInt(st.nextToken());
+        }
+
+        int answer=0, l=0;
+
+        for (int i=1; i<w-1; i++){
+            l = Math.max(l, height[i-1]);
+            int r = 0;
+            for (int j=i+1; j<w; j++){
+                r = Math.max(r, height[j]);
+            }
+
+            if (height[i] < l && height[i] < r) answer+=Math.min(l, r)-height[i];
+        }
+
+        System.out.println(answer);
+    }
+}
+```