[20251223] BOJ / G4 / 합집합 / 권혁준

khj20006/202512/23 BOJ G4 합집합.md

@@ -0,0 +1,57 @@
+```java
+import java.util.*;
+import java.io.*;
+
+public class Main {
+
+    static BufferedReader br;
+    static BufferedWriter bw;
+    static StringTokenizer st;
+
+    static int N;
+    static long[][] arr;
+
+    public static void main(String[] args) throws Exception {
+        bw = new BufferedWriter(new OutputStreamWriter(System.out));
+
+        input();
+        solve();
+
+        bw.close();
+    }
+
+    public static void input() throws Exception {
+        br = new BufferedReader(new InputStreamReader(System.in));
+
+        N = Integer.parseInt(br.readLine());
+        arr = new long[N][];
+        for(int i=0;i<N;i++) {
+            st = new StringTokenizer(br.readLine());
+            arr[i] = new long[]{Long.parseLong(st.nextToken())/2, Long.parseLong(st.nextToken())/2};
+        }
+
+        br.close();
+    }
+
+    public static void solve() throws Exception {
+        bw = new BufferedWriter(new OutputStreamWriter(System.out));
+
+        Arrays.sort(arr, (a,b) -> {
+            if(a[0] == b[0]) return Long.compare(a[1], b[1]);
+            return Long.compare(b[0], a[0]);
+        });
+        long ans = 0, prev = 0;
+        for(long[] point : arr) {
+            long x = point[0], y = point[1];
+            if(y > prev) {
+                ans += (y-prev) * x;
+                prev = y;
+            }
+        }
+        bw.write((ans*4) + "\n");
+
+        bw.close();
+    }
+
+}
+```