結果

問題 No.1785 Inequality Signs
コンテスト
ユーザー hiromi_ayase
提出日時 2021-12-14 04:20:37
言語 Java
(openjdk 23)
結果
TLE  
実行時間 -
コード長 5,094 bytes
コンパイル時間 2,531 ms
コンパイル使用メモリ 86,956 KB
実行使用メモリ 61,308 KB
最終ジャッジ日時 2024-07-23 04:40:27
合計ジャッジ時間 6,538 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge4
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 2
other TLE * 1 -- * 51
権限があれば一括ダウンロードができます

ソースコード

diff # 

import java.util.*;

@SuppressWarnings("unused")
public class Main {

  private static void solve() {
    int n = ni() - 1;
    int k = ni() - 1;

    long sa = 0;
    long cur = 1;
    for (int i = 0; i <= k; i++) {
      sa += cur;
      sa %= mod;
      int x = n + i + 1;
      int y = x - n;
      cur = y >= 0 ? cur * x % mod * inv(y, mod) % mod : 0;
    }


    long[] a = new long[n + 1];
    a[0] = combNative(n + k, n);
    long sa2 = a[0];
    for (int i = 0; i < n; i ++) {
      int x = n + k - i;
      int y = x - n;
      a[i + 1] = y >= 0 ? a[i] * y % mod * inv(x, mod) % mod : 0;
      sa2 += a[i + 1];
    }

    long sb = pow(2, n, mod);
    long[] b = new long[n + 1];
    for (int i = 0; i <= n; i++) {
      b[i] = CX(n, i, mod, fif);
    }

    long ans = sa * sb % mod;
    for (int i = 0; i < n; i++) {
      sa2 += mod - a[n - i];
      sa2 %= mod;

      ans += mod - sa2 * b[i] % mod;
      ans %= mod;
    }
    System.out.println(ans);
  }

  public static long inv(long a, int p)
	{
		long ret = 1;
		long mul = a;
		for(long n = p-2;n > 0;n >>>= 1){
			if((n&1)==1)ret = ret * mul % p;
			mul = mul * mul % p;
		}
		return ret;
	}

  private static long combNative(long n, int r) {
    long x = 1;
    long y = 1;
    for (int i = 0; i < r; i++) {
      x *= n - i;
      x %= mod;
      y *= i + 1;
      y %= mod;
    }
    return x * pow(y, mod - 2, mod) % mod;
  }

  private static long pow(long x, long n, int m) {
    if (m == 1)
      return 0;
    long r = 1;
    long y = x % m;
    while (n > 0) {
      if ((n & 1) != 0)
        r = (r * y) % m;
      y = (y * y) % m;
      n >>= 1;
    }
    return r;
  }

  private static int mod = 1000000007;
  private static int[][] fif = enumFIF(300000, mod);

  public static long CX(long n, long r, int p, int[][] fif) {
    if (n < 0 || r < 0 || r > n)
      return 0;
    int np = (int) (n % p), rp = (int) (r % p);
    if (np < rp)
      return 0;
    if (n == 0 && r == 0)
      return 1;
    int nrp = np - rp;
    if (nrp < 0)
      nrp += p;
    return (long) fif[0][np] * fif[1][rp] % p * fif[1][nrp] % p * CX(n / p, r / p, p, fif) % p;
  }

  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 void main(String[] args) {
    new Thread(null, new Runnable() {
      @Override
      public void run() {
        long start = System.currentTimeMillis();
        String debug = args.length > 0 ? args[0] : null;
        if (debug != null) {
          try {
            is = java.nio.file.Files.newInputStream(java.nio.file.Paths.get(debug));
          } catch (Exception e) {
            throw new RuntimeException(e);
          }
        }
        reader = new java.io.BufferedReader(new java.io.InputStreamReader(is), 32768);
        solve();
        out.flush();
        tr((System.currentTimeMillis() - start) + "ms");
      }
    }, "", 64000000).start();
  }

  private static java.io.InputStream is = System.in;
  private static java.io.PrintWriter out = new java.io.PrintWriter(System.out);
  private static java.util.StringTokenizer tokenizer = null;
  private static java.io.BufferedReader reader;

  public static String next() {
    while (tokenizer == null || !tokenizer.hasMoreTokens()) {
      try {
        tokenizer = new java.util.StringTokenizer(reader.readLine());
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }
    return tokenizer.nextToken();
  }

  private static double nd() {
    return Double.parseDouble(next());
  }

  private static long nl() {
    return Long.parseLong(next());
  }

  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 char[] ns() {
    return next().toCharArray();
  }

  private static long[] nal(int n) {
    long[] a = new long[n];
    for (int i = 0; i < n; i++)
      a[i] = nl();
    return a;
  }

  private static int[][] ntable(int n, int m) {
    int[][] table = new int[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[i][j] = ni();
      }
    }
    return table;
  }

  private static int[][] nlist(int n, int m) {
    int[][] table = new int[m][n];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[j][i] = ni();
      }
    }
    return table;
  }

  private static int ni() {
    return Integer.parseInt(next());
  }

  private static void tr(Object... o) {
    if (is != System.in)
      System.out.println(java.util.Arrays.deepToString(o));
  }
}
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