4-mong3125

mong3125/DFS/P023_11724.java

@@ -0,0 +1,61 @@
+package CH05_탐색;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+public class P023_11724 {
+    static int N, M;
+    static boolean[][] edges;
+    static boolean[] cache;
+
+    public static void main(String[] args) throws IOException {
+        // 입력
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        // 노드의 수, 엣지의 수 입력
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+
+        edges = new boolean[N + 1][N + 1];
+        cache = new boolean[N + 1];
+
+        // 엣지 입력
+        for (int i = 0; i < M; i++) {
+            st = new StringTokenizer(br.readLine());
+            int a = Integer.parseInt(st.nextToken());
+            int b = Integer.parseInt(st.nextToken());
+
+            // 양방향 입력
+            edges[a][b] = true;
+            edges[b][a] = true;
+        }
+
+        int count = 0;
+        for (int i = 1; i <= N; i++) {
+            if (dfs(i)) {
+                count++;
+            }
+        }
+
+        System.out.println(count);
+
+        br.close();
+    }
+
+    public static boolean dfs(int id) {
+        if (cache[id]) return false;
+
+        cache[id] = true;
+
+        for (int i = 1; i <= N; i++) {
+            if (edges[id][i]) {
+                dfs(i);
+            }
+        }
+
+        return true;
+    }
+}