[백준 12893] 적의 적 - 이분 그래프

Author: HiiWee

hoseok/week78/Boj12893.java

@@ -0,0 +1,74 @@
+import java.io.*;
+import java.util.*;
+
+class Main {
+
+    static int n, m;
+    static List<Integer>[] graph;
+    static int[] visited;
+
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        n = Integer.parseInt(st.nextToken());
+        m = Integer.parseInt(st.nextToken());
+
+        graph = new ArrayList[n + 1];
+        for (int i = 0; i <= n; i++) {
+            graph[i] = new ArrayList<>();
+        }
+
+        for (int i = 0; i < m; i++) {
+            st = new StringTokenizer(br.readLine());
+            int a = Integer.parseInt(st.nextToken());
+            int b = Integer.parseInt(st.nextToken());
+            graph[a].add(b);
+            graph[b].add(a);
+        }
+
+        visited = new int[n + 1];
+        Arrays.fill(visited, -1);
+
+        boolean answer = true;
+        for (int i = 1; i <= n; i++) {
+            if (visited[i] == -1) {
+                if (!search(i)) {
+                    answer = false;
+                    break;
+                }
+            }
+        }
+
+        bw.write(answer ? "1" : "0");
+        bw.flush();
+        bw.close();
+    }
+
+    public static boolean search(int number) {
+        visited[number] = 0;
+        Queue<Integer> que = new ArrayDeque<>();
+        que.offer(number);
+        boolean isPossible = true;
+
+        while (!que.isEmpty() && isPossible) {
+            int current = que.poll();
+
+            for (int next : graph[current]) {
+                int nextFlag = (visited[current] + 1) % 2;
+
+                if (visited[next] != -1) {
+                    if (visited[next] != nextFlag) {
+                        isPossible = false;
+                        break;
+                    }
+                } else {
+                    visited[next] = nextFlag;
+                    que.offer(next);
+                }
+            }
+        }
+
+        return isPossible;
+    }
+}