Merge pull request #26 from AlgoLeadMe/7-mong3

7-mong3

mong3125/DFS/BOJ13023.java

@@ -0,0 +1,61 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.StringTokenizer;
+
+public class BOJ13023 {
+
+    static int N, M;    // 사람의 수, 친구 관계 수
+    static List<Integer>[] friends;
+    static boolean[] visited;   // 방문한 노드인지
+    static boolean isExist = false;
+
+    public static void main(String[] args) throws IOException {
+        // 입력
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+        friends = new ArrayList[N];
+        for (int i = 0; i < N; i++) {
+            friends[i] = new ArrayList<>();
+        }
+        visited = new boolean[N+1];
+
+        // 양방향 친구관계 맺어주기
+        for (int i = 0; i < M; i++) {
+            st = new StringTokenizer(br.readLine());
+            int a = Integer.parseInt(st.nextToken());
+            int b = Integer.parseInt(st.nextToken());
+
+            friends[a].add(b);
+            friends[b].add(a);
+        }
+
+        for (int i = 0; i < N; i++) {
+            dfs(i, 1);
+            if (isExist) break;
+        }
+
+        int answer = isExist ? 1 : 0;
+        System.out.println(answer);
+    }
+
+    public static void dfs(int personId, int depth) {
+        if (depth >= 5 || isExist) {
+            isExist = true;
+            return;
+        }
+
+        visited[personId] = true;
+        for (int i : friends[personId]) {
+            if (!visited[i]) {
+                dfs(i, depth + 1);
+            }
+        }
+        visited[personId] = false;
+    }
+}