Merge pull request #929 from AlgorithmWithGod/Ukj0ng

[20250919] BOJ / G5 / 현수막 걸기 / 한종욱

Author: ShinHeeEul

Ukj0ng/202509/19 BOJ G5 현수막 걸기.md

@@ -0,0 +1,80 @@
+```
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    private static final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    private static final BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    private static int[] piles, flagpole;
+    private static double answer;
+    private static int N, M, R;
+
+    public static void main(String[] args) throws IOException {
+        init();
+
+        for (int i = 0; i < N-1; i++) {
+            for (int j = i+1; j < N; j++) {
+                checkTriangle(i, j);
+            }
+        }
+
+        if (answer < 0) {
+            bw.write("-1\n");
+        } else {
+            bw.write(String.format("%.1f\n", answer));
+        }
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static void init() throws IOException {
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+        R = Integer.parseInt(st.nextToken());
+        answer = -1;
+
+        piles = new int[N];
+        flagpole = new int[M];
+
+        st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < N; i++) {
+            piles[i] = Integer.parseInt(st.nextToken()) + 20000;
+        }
+
+        st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < M; i++) {
+            flagpole[i] = Integer.parseInt(st.nextToken());
+        }
+
+        Arrays.sort(piles);
+        Arrays.sort(flagpole);
+    }
+
+    private static void checkTriangle(int i, int j) {
+        int width = piles[j] - piles[i];
+        
+        double maxHeight = 2.0 * R / width;
+
+        int left = 0, right = M - 1;
+        int bestIdx = -1;
+        
+        while (left <= right) {
+            int mid = left + (right - left) / 2;
+            if (flagpole[mid] <= maxHeight) {
+                bestIdx = mid;
+                left = mid + 1;
+            } else {
+                right = mid - 1;
+            }
+        }
+        
+        if (bestIdx >= 0) {
+            double area = (double)width * flagpole[bestIdx] / 2.0;
+            answer = Math.max(answer, area);
+        }
+    }
+}
+```