Submission #98213

---

Source Code Expand

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class Main {
	static InputStream is;
	static PrintWriter out;
	static String INPUT = "";
	
	static void solve()
	{
		int K = ni(), n = ni();
		int mod = 1000000007;
		out.println(lrx(K, n-1, mod));
	}
	
	public static long lrx(int m, long n, long mod)
	{
//		long[][] m2 = new long[m-1][m];
		int[][] m2 = new int[m-1][m];
		Arrays.fill(m2[0], 1);
		for(int i = 1;i < m-1;i++){
			for(int j = 0;j < m;j++){
				int x = m2[i-1][m-1];
				if(j-1 >= 0)x += m2[i-1][j-1];
				if(x >= mod)x -= mod;
				m2[i][j] = x;
			}
		}
		
		long[] ret = new long[m];
		ret[0] = 1;
		long[] temp = new long[2*m];
		for(int l = 31;l >= 0;l--){
			if(n<<63-l<0){
				for(int i = 0;i < m;i++)temp[i] = ret[m-1];
				for(int i = 1;i < m;i++)temp[i] += ret[i-1];
				for(int i = 0;i < m;i++){
					ret[i] = temp[i];
					if(ret[i] >= mod)ret[i] -= mod;
				}
			}
			if(l > 0){
				Arrays.fill(temp, 0L);
				for(int i = 0;i < m;i++){
					if(ret[i] == 0)continue;
					for(int j = 0;j < m;j++){
						if(ret[j] == 0)continue;
						temp[i+j] += ret[i] * ret[j];// % mod;
//						temp[i+j] += ret[i] * ret[j];
						if(temp[i+j] >= 8000000000000000000L){
							temp[i+j] %= mod;
						}
//						}else{
//							tr(temp[i+j]);
//						}
					}
				}
				for(int i = 0;i < 2*m;i++){
					temp[i] %= mod;
				}
				for(int i = 0;i < m;i++){
					long s = temp[i];
					for(int j = m;j < 2*m-1;j++){
						s += temp[j] * m2[j-m][i];// % mod;
						if(s >= 8000000000000000000L)s %= mod;
					}
					ret[i] = s % mod;
				}
			}
		}
		
		long s = 0;
		for(int i = 0;i < m;i++){
			s += ret[i];
		}
		return s % mod;
	}
	
	public static void main(String[] args) throws Exception
	{
		long S = System.currentTimeMillis();
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		solve();
		out.flush();
		long G = System.currentTimeMillis();
		tr(G-S+"ms");
	}
	
	private static boolean eof()
	{
		if(lenbuf == -1)return true;
		int lptr = ptrbuf;
		while(lptr < lenbuf)if(!isSpaceChar(inbuf[lptr++]))return false;
		
		try {
			is.mark(1000);
			while(true){
				int b = is.read();
				if(b == -1){
					is.reset();
					return true;
				}else if(!isSpaceChar(b)){
					is.reset();
					return false;
				}
			}
		} catch (IOException e) {
			return true;
		}
	}
	
	private static byte[] inbuf = new byte[1024];
	static int lenbuf = 0, ptrbuf = 0;
	
	private static int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private static boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private static int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private static double nd() { return Double.parseDouble(ns()); }
	private static char nc() { return (char)skip(); }
	
	private static String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private static char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private static char[][] nm(int n, int m)
	{
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private static int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private static int ni()
	{
		int num = 0, b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { if(INPUT.length() != 0)System.out.println(Arrays.deepToString(o)); }
}

Submission Info

Judge Result