Merge pull request #1824 from AlgorithmWithGod/ksinji

[20260124] BOJ / G4 / 거짓말 / 강신지

Author: ShinHeeEul

ksinji/202601/24 BOJ 거짓말.md

@@ -0,0 +1,83 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    static int n, m;
+    static int[] parent;
+
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        n = Integer.parseInt(st.nextToken());
+        m = Integer.parseInt(st.nextToken());
+
+        parent = new int[n + 1];
+        for (int i = 1; i <= n; i++) parent[i] = i;
+
+        st = new StringTokenizer(br.readLine());
+        int truthCnt = Integer.parseInt(st.nextToken());
+        int[] truth = new int[truthCnt];
+        for (int i = 0; i < truthCnt; i++) {
+            truth[i] = Integer.parseInt(st.nextToken());
+        }
+
+        if (truthCnt == 0) {
+            for (int i = 0; i < m; i++) {
+                br.readLine();
+            }
+            System.out.println(m);
+            return;
+        }
+
+        for (int i = 1; i < truthCnt; i++) {
+            union(truth[0], truth[i]);
+        }
+
+        int[][] party = new int[m][];
+        for (int i = 0; i < m; i++) {
+            st = new StringTokenizer(br.readLine());
+            int k = Integer.parseInt(st.nextToken());
+            int[] member = new int[k];
+            for (int j = 0; j < k; j++) {
+                member[j] = Integer.parseInt(st.nextToken());
+            }
+            party[i] = member;
+
+            for (int j = 1; j < k; j++) {
+                union(member[0], member[j]);
+            }
+        }
+
+        int truthGroup = find(truth[0]);
+        int ans = 0;
+
+        for (int i = 0; i < m; i++) {
+            boolean ok = true;
+            for (int person : party[i]) {
+                if (find(person) == truthGroup) {
+                    ok = false;
+                    break;
+                }
+            }
+            if (ok) ans++;
+        }
+
+        System.out.println(ans);
+    }
+
+    static int find(int x) {
+        if (parent[x] == x) return x;
+        return parent[x] = find(parent[x]);
+    }
+
+    static void union(int a, int b) {
+        a = find(a);
+        b = find(b);
+        if (a == b) return;
+        parent[b] = a;
+    }
+}
+
+```