Merge pull request #586 from AlgorithmWithGod/JHLEE325

[20250801] BOJ / G4 / 키 순서 / 이준희

Author: ShinHeeEul

JHLEE325/202508/01 BOJ G4 키 순서.md

@@ -0,0 +1,49 @@
+```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 n = Integer.parseInt(st.nextToken());
+        int m = Integer.parseInt(st.nextToken());
+        boolean[][] arr = new boolean[n][n];
+
+        for (int i = 0; i < m; i++) {
+            st = new StringTokenizer(br.readLine());
+            int a = Integer.parseInt(st.nextToken()) - 1;
+            int b = Integer.parseInt(st.nextToken()) - 1;
+            arr[a][b] = true;
+        }
+
+        for (int k = 0; k < n; k++) {
+            for (int i = 0; i < n; i++) {
+                for (int j = 0; j < n; j++) {
+                    if (arr[i][k] && arr[k][j])
+                        arr[i][j] = true;
+                }
+            }
+        }
+
+        int cnt = 0;
+        for (int i = 0; i < n; i++) {
+            boolean isknow = true;
+            for (int j = 0; j < n; j++) {
+                if (i == j)
+                    continue;
+                if (!arr[i][j] && !arr[j][i])
+                    isknow = false;
+            }
+            if (isknow)
+                cnt++;
+        }
+
+        System.out.println(cnt);
+    }
+
+}
+
+```