[20250306] BOJ / P4 / My뷰 꾸미기 / 권혁준

khj20006/202503/06 BOJ P4 My뷰 꾸미기.md

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+```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 int N;
+	static long ans = 1;
+	static long[] fac = new long[600001];
+	static final long mod = (long)1e9 + 7;
+
+
+	public static void main(String[] args) throws Exception {
+
+		ready();
+		solve();
+
+		bwEnd();
+
+	}
+
+	static void ready() throws Exception{
+
+		N = Integer.parseInt(br.readLine());
+		fac[0] = 1;
+		for(int i=1;i<=600000;i++) fac[i] = (fac[i-1] * i) % mod;
+
+	}
+
+	static void solve() throws Exception{
+
+		while(N-- > 0) {
+			nextLine();
+			int a = nextInt(), b = nextInt();
+			ans = (ans * (comb(a+b,a) + mod - 1)) % mod;
+		}
+		bw.write(ans + "\n");
+
+	}
+
+	static long comb(int x, int y) {
+
+		return fac[x] * power(fac[x-y], mod-2) % mod * power(fac[y], mod-2) % mod;
+
+	}
+
+	// x^p % mod
+	static long power(long x, long p) {
+		if(p == 0) return 1;
+		if(p == 1) return x % mod;
+		long half = power(x,p>>1) % mod;
+		half = half * half % mod;
+		if(p%2==0) return half;
+		return half * x % mod;
+	}
+
+}
+
+```