2011年 冬合宿4日目 Problem E : Rabbit Game Playing [Licence: NYSL Version 0.9982]

Main.java

import static java.util.Arrays.*;

public class Main {
  public static void main(String... args) {
		new Main().run();
	}

	static final long MOD = 1000 * 1000 * 1000 + 7;

	public void run() {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int T = sc.nextInt();
		int[] D = new int[N];
		for(int i = 0; i < N; i++)
			D[i] = sc.nextInt();
		sort(D);
		long ans = 1L;
		for(int i = 0, j = 0; i < N; i++) {
			while(j < N && D[j] <= D[i] + T)
				j++;
			ans *= j - i;
			ans %= MOD;
		}
		System.out.println(ans);
	}
}

class Scanner {
	final java.util.Scanner sc;

	public Scanner(java.io.InputStream is) {
		this.sc = new java.util.Scanner(is);
	}

	public int nextInt() {
		return Integer.parseInt(sc.next());
	}
}