結果

問題 No.1785 Inequality Signs
ユーザー 👑 hos.lyrichos.lyric
提出日時 2021-12-14 00:08:06
言語 D
(dmd 2.107.1)
結果
AC  
実行時間 72 ms / 2,000 ms
コード長 4,409 bytes
コンパイル時間 1,533 ms
コンパイル使用メモリ 152,756 KB
実行使用メモリ 8,736 KB
最終ジャッジ日時 2023-09-04 15:19:30
合計ジャッジ時間 5,707 ms
ジャッジサーバーID
（参考情報） 		judge12 / judge14
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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 13 ms
7,988 KB
testcase_01 AC 18 ms
8,040 KB
testcase_02 AC 55 ms
8,028 KB
testcase_03 AC 60 ms
8,124 KB
testcase_04 AC 13 ms
7,968 KB
testcase_05 AC 36 ms
7,988 KB
testcase_06 AC 65 ms
8,044 KB
testcase_07 AC 14 ms
8,540 KB
testcase_08 AC 57 ms
8,032 KB
testcase_09 AC 22 ms
8,408 KB
testcase_10 AC 46 ms
7,968 KB
testcase_11 AC 22 ms
8,060 KB
testcase_12 AC 31 ms
8,540 KB
testcase_13 AC 20 ms
8,040 KB
testcase_14 AC 38 ms
8,032 KB
testcase_15 AC 34 ms
8,044 KB
testcase_16 AC 28 ms
7,980 KB
testcase_17 AC 45 ms
8,072 KB
testcase_18 AC 47 ms
8,460 KB
testcase_19 AC 40 ms
8,084 KB
testcase_20 AC 40 ms
7,956 KB
testcase_21 AC 39 ms
8,024 KB
testcase_22 AC 22 ms
8,640 KB
testcase_23 AC 28 ms
8,156 KB
testcase_24 AC 72 ms
8,120 KB
testcase_25 AC 36 ms
8,736 KB
testcase_26 AC 31 ms
7,964 KB
testcase_27 AC 55 ms
8,092 KB
testcase_28 AC 54 ms
8,304 KB
testcase_29 AC 54 ms
8,684 KB
testcase_30 AC 54 ms
7,992 KB
testcase_31 AC 54 ms
8,236 KB
testcase_32 AC 54 ms
7,984 KB
testcase_33 AC 12 ms
8,124 KB
testcase_34 AC 13 ms
7,964 KB
testcase_35 AC 13 ms
8,116 KB
testcase_36 AC 35 ms
8,636 KB
testcase_37 AC 17 ms
8,040 KB
testcase_38 AC 18 ms
8,072 KB
testcase_39 AC 17 ms
8,160 KB
testcase_40 AC 20 ms
8,120 KB
testcase_41 AC 22 ms
8,044 KB
testcase_42 AC 38 ms
8,440 KB
testcase_43 AC 50 ms
8,604 KB
testcase_44 AC 44 ms
8,200 KB
testcase_45 AC 16 ms
8,244 KB
testcase_46 AC 19 ms
8,552 KB
testcase_47 AC 18 ms
8,084 KB
testcase_48 AC 23 ms
8,004 KB
testcase_49 AC 13 ms
8,080 KB
testcase_50 AC 42 ms
7,960 KB
testcase_51 AC 15 ms
8,120 KB
testcase_52 AC 14 ms
8,664 KB
testcase_53 AC 16 ms
8,040 KB
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ソースコード

diff # 

import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }

struct ModInt(uint M_) {
  import std.conv : to;
  alias M = M_;
  uint x;
  this(ModInt a) { x = a.x; }
  this(uint x_) { x = x_ % M; }
  this(ulong x_) { x = x_ % M; }
  this(int x_) { x = ((x_ %= cast(int)(M)) < 0) ? (x_ + cast(int)(M)) : x_; }
  this(long x_) { x = cast(uint)(((x_ %= cast(long)(M)) < 0) ? (x_ + cast(long)(M)) : x_); }
  ref ModInt opAssign(T)(inout(T) a) if (is(T == uint) || is(T == ulong) || is(T == int) || is(T == long)) { return this = ModInt(a); }
  ref ModInt opOpAssign(string op, T)(T a) {
    static if (is(T == ModInt)) {
      static if (op == "+") { x = ((x += a.x) >= M) ? (x - M) : x; }
      else static if (op == "-") { x = ((x -= a.x) >= M) ? (x + M) : x; }
      else static if (op == "*") { x = cast(uint)((cast(ulong)(x) * a.x) % M); }
      else static if (op == "/") { this *= a.inv(); }
      else static assert(false);
      return this;
    } else static if (op == "^^") {
      if (a < 0) return this = inv()^^(-a);
      ModInt b = this, c = 1U;
      for (long e = a; e; e >>= 1) { if (e & 1) c *= b; b *= b; }
      return this = c;
    } else {
      return mixin("this " ~ op ~ "= ModInt(a)");
    }
  }
  ModInt inv() const {
    uint a = M, b = x; int y = 0, z = 1;
    for (; b; ) { const q = a / b; const c = a - q * b; a = b; b = c; const w = y - cast(int)(q) * z; y = z; z = w; }
    assert(a == 1); return ModInt(y);
  }
  ModInt opUnary(string op)() const {
    static if (op == "+") { return this; }
    else static if (op == "-") { ModInt a; a.x = x ? (M - x) : 0U; return a; }
    else static assert(false);
  }
  ModInt opBinary(string op, T)(T a) const { return mixin("ModInt(this) " ~ op ~ "= a"); }
  ModInt opBinaryRight(string op, T)(T a) const { return mixin("ModInt(a) " ~ op ~ "= this"); }
  bool opCast(T: bool)() const { return (x != 0U); }
  string toString() const { return x.to!string; }
}

enum MO = 10^^9 + 7;
alias Mint = ModInt!MO;

enum LIM = 4 * 10^^5 + 10;
Mint[] inv, fac, invFac;
void prepare() {
  inv = new Mint[LIM];
  fac = new Mint[LIM];
  invFac = new Mint[LIM];
  inv[1] = 1;
  foreach (i; 2 .. LIM) {
    inv[i] = -((Mint.M / i) * inv[cast(size_t)(Mint.M % i)]);
  }
  fac[0] = invFac[0] = 1;
  foreach (i; 1 .. LIM) {
    fac[i] = fac[i - 1] * i;
    invFac[i] = invFac[i - 1] * inv[i];
  }
}
Mint binom(long n, long k) {
  if (n < 0) {
    if (k >= 0) {
      return (-1)^^(k & 1) * binom(-n + k - 1, k);
    } else if (n - k >= 0) {
      return (-1)^^((n - k) & 1) * binom(-k - 1, n - k);
    } else {
      return Mint(0);
    }
  } else {
    if (0 <= k && k <= n) {
      assert(n < LIM);
      return fac[cast(size_t)(n)] * invFac[cast(size_t)(k)] * invFac[cast(size_t)(n - k)];
    } else {
      return Mint(0);
    }
  }
}


void main() {
  prepare;
  
  try {
    for (; ; ) {
      const N = readInt;
      const K = readInt;
      
      // binom(K + N - 1, N)
      Mint bn = 1;
      foreach (i; 0 .. N) {
        bn *= (K + N - 1 - i);
        bn *= inv[1 + i];
      }
      Mint ans;
      foreach_reverse (a; 0 .. N) {
        if (!bn) {
          break;
        }
        ans += binom(N - 1, a) * bn;
        bn /= (K + a);
        bn *= (K + a - N);
      }
      writeln(ans);
    }
  } catch (EOFException e) {
  }
}
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