結果

問題 No.827 総神童数
ユーザー uwiuwi
提出日時 2019-05-04 04:27:05
言語 Java21
(openjdk 21)
結果
AC  
実行時間 397 ms / 2,000 ms
コード長 5,480 bytes
コンパイル時間 3,898 ms
コンパイル使用メモリ 82,160 KB
実行使用メモリ 64,120 KB
最終ジャッジ日時 2023-09-01 22:45:30
合計ジャッジ時間 16,119 ms
ジャッジサーバーID
（参考情報） 		judge13 / judge14
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 60 ms
51,140 KB
testcase_01 AC 61 ms
50,876 KB
testcase_02 AC 61 ms
51,012 KB
testcase_03 AC 61 ms
50,856 KB
testcase_04 AC 61 ms
50,920 KB
testcase_05 AC 60 ms
50,884 KB
testcase_06 AC 60 ms
50,888 KB
testcase_07 AC 61 ms
50,972 KB
testcase_08 AC 62 ms
50,956 KB
testcase_09 AC 370 ms
64,012 KB
testcase_10 AC 219 ms
57,312 KB
testcase_11 AC 73 ms
53,020 KB
testcase_12 AC 124 ms
54,624 KB
testcase_13 AC 355 ms
62,512 KB
testcase_14 AC 79 ms
53,308 KB
testcase_15 AC 194 ms
55,300 KB
testcase_16 AC 365 ms
62,048 KB
testcase_17 AC 397 ms
61,968 KB
testcase_18 AC 213 ms
57,160 KB
testcase_19 AC 386 ms
63,864 KB
testcase_20 AC 347 ms
62,080 KB
testcase_21 AC 310 ms
58,580 KB
testcase_22 AC 372 ms
62,724 KB
testcase_23 AC 68 ms
50,956 KB
testcase_24 AC 362 ms
62,576 KB
testcase_25 AC 340 ms
60,244 KB
testcase_26 AC 368 ms
61,912 KB
testcase_27 AC 297 ms
60,144 KB
testcase_28 AC 269 ms
60,060 KB
testcase_29 AC 247 ms
57,200 KB
testcase_30 AC 117 ms
52,088 KB
testcase_31 AC 215 ms
57,552 KB
testcase_32 AC 215 ms
57,400 KB
testcase_33 AC 366 ms
64,116 KB
testcase_34 AC 363 ms
61,912 KB
testcase_35 AC 212 ms
57,092 KB
testcase_36 AC 275 ms
57,976 KB
testcase_37 AC 338 ms
60,612 KB
testcase_38 AC 362 ms
64,120 KB
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ソースコード

diff # 

package contest190503;
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 C {
	InputStream is;
	PrintWriter out;
	String INPUT = "";
	
	// 0414-
	void solve()
	{
		int n = ni();
		int[] from = new int[n - 1];
		int[] to = new int[n - 1];
		for (int i = 0; i < n - 1; i++) {
			from[i] = ni() - 1;
			to[i] = ni() - 1;
		}
		int[][] g = packU(n, from, to);
		int[][] pars = parents3(g, 0);
		int[] par = pars[0], ord = pars[1], dep = pars[2];
		
//		 n*C(n-1,d)/C(n-1,d) + (n-1)*C(n-2,d)/C(n-1,d) + ...
		// C(n-1,d)/C(n-1,d) + C(n-2,d)/C(n-1,d) + ...
		// C(n,d+1)
		
		int mod = 1000000007;
		int[][] fif = enumFIF(200005, mod);
		long all = 0;
		for(int i = 0;i < n;i++) {
			all += C(n, dep[i]+1, mod, fif) * invl(C(n-1, dep[i], mod, fif), mod);
			all %= mod;
		}
		all = all * fif[0][n-1] % mod;
		
		out.println(all);
	}
	
	public static long invl(long a, long mod) {
		long b = mod;
		long p = 1, q = 0;
		while (b > 0) {
			long c = a / b;
			long d;
			d = a;
			a = b;
			b = d % b;
			d = p;
			p = q;
			q = d - c * q;
		}
		return p < 0 ? p + mod : p;
	}
	
	public static long C(int n, int r, int mod, int[][] fif) {
		if (n < 0 || r < 0 || r > n)
			return 0;
		return (long) fif[0][n] * fif[1][r] % mod * fif[1][n - r] % mod;
	}

	
	
	public static int[][] enumFIF(int n, int mod) {
		int[] f = new int[n + 1];
		int[] invf = new int[n + 1];
		f[0] = 1;
		for (int i = 1; i <= n; i++) {
			f[i] = (int) ((long) f[i - 1] * i % mod);
		}
		long a = f[n];
		long b = mod;
		long p = 1, q = 0;
		while (b > 0) {
			long c = a / b;
			long d;
			d = a;
			a = b;
			b = d % b;
			d = p;
			p = q;
			q = d - c * q;
		}
		invf[n] = (int) (p < 0 ? p + mod : p);
		for (int i = n - 1; i >= 0; i--) {
			invf[i] = (int) ((long) invf[i + 1] * (i + 1) % mod);
		}
		return new int[][] { f, invf };
	}



	public static int[][] parents3(int[][] g, int root) {
		int n = g.length;
		int[] par = new int[n];
		Arrays.fill(par, -1);

		int[] depth = new int[n];
		depth[0] = 0;

		int[] q = new int[n];
		q[0] = root;
		for (int p = 0, r = 1; p < r; p++) {
			int cur = q[p];
			for (int nex : g[cur]) {
				if (par[cur] != nex) {
					q[r++] = nex;
					par[nex] = cur;
					depth[nex] = depth[cur] + 1;
				}
			}
		}
		return new int[][] { par, q, depth };
	}

	static int[][] packU(int n, int[] from, int[] to) {
		int[][] g = new int[n][];
		int[] p = new int[n];
		for (int f : from)
			p[f]++;
		for (int t : to)
			p[t]++;
		for (int i = 0; i < n; i++)
			g[i] = new int[p[i]];
		for (int i = 0; i < from.length; i++) {
			g[from[i]][--p[from[i]]] = to[i];
			g[to[i]][--p[to[i]]] = from[i];
		}
		return g;
	}

	
	void run() throws Exception
	{
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//		Thread t = new Thread(null, null, "~", Runtime.getRuntime().maxMemory()){
//			@Override
//			public void run() {
//				long s = System.currentTimeMillis();
//				solve();
//				out.flush();
//				if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//			}
//		};
//		t.start();
//		t.join();
	}
	
	public static void main(String[] args) throws Exception { new C().run(); }
	
	private byte[] inbuf = new byte[1024];
	public int lenbuf = 0, ptrbuf = 0;
	
	private 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 boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private 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 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 int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private long[] nal(int n)
	{
		long[] a = new long[n];
		for(int i = 0;i < n;i++)a[i] = nl();
		return a;
	}
	
	private 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 int[][] nmi(int n, int m) {
		int[][] map = new int[n][];
		for(int i = 0;i < n;i++)map[i] = na(m);
		return map;
	}
	
	private int ni() { return (int)nl(); }
	
	private 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) { System.out.println(Arrays.deepToString(o)); }
}
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