[20250210] BOJ / 플래5 / 인간관계 / 권혁준

Author: oncsr

khj20006/202502/10 BOJ P5 인간관계.md

@@ -0,0 +1,80 @@
+```java
+
+import java.util.*;
+import java.io.*;
+
+class Main {
+	
+	// IO field
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st;
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static int nextInt() {return Integer.parseInt(st.nextToken());}
+	static long nextLong() {return Long.parseLong(st.nextToken());}
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+	
+	// Additional field
+	static long[] dp;
+	static long[] s;
+	static int[] root;
+	static int N, M;
+	static final long mod = (int)1e9 + 7;
+	
+	static int f(int x) { return x==root[x] ? x : (root[x]=f(root[x])); }
+	
+	public static void main(String[] args) throws Exception {
+		
+		ready();
+		solve();
+	
+		bwEnd();
+	}
+	
+	static void ready() throws Exception{
+
+		nextLine();
+		N = nextInt();
+		M = nextInt();
+		dp = new long[N+1];
+		s = new long[N+1];
+		root = new int[N+1];
+		for(int i=1;i<=N;i++) root[i] = i;
+		
+	}
+	
+	static void solve() throws Exception{
+		
+		dp[1] = 1;
+		s[1] = 1;
+		for(int i=2;i<=N;i++) {
+			long[] ndp = new long[N+1];
+			ndp[1] = 1;
+			ndp[i] = 1;
+			for(int j=2;j<i;j++) {
+				ndp[j] = (dp[j] * j + dp[j-1]) % mod;
+			}
+			
+			dp = ndp;
+			for(int j=1;j<=i;j++) {
+				s[i] = (s[i] + dp[j]) % mod;
+			}
+		}
+		
+		while(M-- > 0) {
+			nextLine();
+			int a = nextInt(), b = nextInt();
+			int x = f(a), y = f(b);
+			if(x != y) {
+				N--;
+				root[x] = y;
+			}
+			bw.write(s[N] + "\n");
+		}
+		
+	}
+	
+}
+
+```