Submission #766352

#	Time	Username	Problem	Language	Result	Execution time	Memory
766352		Sam_a17	NoM (RMI21_nom)	C++17	100 / 100	92 ms	54308 KiB

Main

#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
// #include <atcoder/all>
#include <cstdio>
using namespace std;
 
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
 
#define sz(x) (int((x).size()))
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
 
#define pb push_back
#define popf pop_front
#define popb pop_back
#define ld long double
#define ll long long
 
void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
void print(long double t) {cerr << t;}
 
template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T> void print(T v[],T n) {cerr << "["; for(int i = 0; i < n; i++) {cerr << v[i] << " ";} cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(deque <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
 
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'
 
// for random generations
mt19937 myrand(chrono::steady_clock::now().time_since_epoch().count());
// mt19937 myrand(131);
 
// for grid problems
int dx[8] = {-1,0,1,0,1,-1,1,-1};
int dy[8] = {0,1,0,-1,1,1,-1,-1};
 
long long ka() {
	long long x = 0;
	bool z = false;
	while (1)
	{
		char y = getchar();
		if (y == '-')
			z = true;
		else if ('0' <= y && y <= '9')
			x = x * 10 + y - '0';
		else
		{
			if (z)
				x *= -1;
			return x;
		}
	}
}
 
// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
  fastIO();
 
  if (str != "") {
    freopen((str + ".in").c_str(), "r", stdin);
    freopen((str + ".out").c_str(), "w", stdout);
  } else if(str == "input") {
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
  }
}
 
// Indexed Set
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = 2005;
long long dp[N][N];

namespace Cnk {
  const long long mod = 1e9 + 7;
  const int bN = 2e6 + 10, maxN = bN - 2;
  long long fact[bN], ifact[bN];

  long long binPowByMod(long long a, long long b) {
    a %= mod;
    long long res = 1;
    while (b > 0) {
      if (b & 1)
        res = res * a % mod;
      a = a * a % mod;
      b >>= 1;
    }
    return res;
  }
  
  long long choose (long long a, long long b) {
    return (((fact[a] * ifact[b]) % mod ) * ifact[a - b] ) % mod;
  }

  void generate() {
    fact[0] = fact[1] = 1;
    for(int i = 2; i < bN; i++) {
      fact[i] = (fact[i - 1] * i) % mod;
    }
  
    ifact[maxN] = binPowByMod(fact[maxN], mod - 2);
    for(int i = maxN; i >= 1; i--) {
      ifact[i - 1] = (ifact[i] * i) % mod;
    }
  }
  
  long long modInverse(long long A, long long M) {
    long long m0 = M;
    long long y = 0, x = 1;

    if (M == 1) return 0;

    while (A > 1) {
      long long q = A / M;
      long long t = M;
      M = A % M, A = t;
      t = y;
      y = x - q * y;
      x = t;
    }
  
    if (x < 0) x += m0;
    return x;
  }

  long long add(long long a, long long b) {
    return (a + b) % mod;
  }

  long long mult(long long a, long long b) {
    return (a * b) % mod;
  }

  long long sub(long long a, long long b) {
    return (a - b + 2 * mod) % mod;
  }

  long long catalan(int n) {
    if(n % 2 == 1) {
      return 0;
    }
    n /= 2;
    long long answ = fact[2 * n];
    answ = mult(answ, ifact[n + 1]);
    answ = mult(answ, ifact[n]);
    return answ;
  }

  // random
  long long hsh() {
    return (((long long)myrand()) << 31) ^ (myrand());
  }
}

using namespace Cnk;

void solve_() {
  int n, m; cin >> n >> m;

  if(m == 1) {
    cout << 0 << '\n';
    return;
  }

  vector<int> a;
  for(int i = 1; i <= 2 * n; i++) {
    a.push_back(i);
  }

  vector<int> cnt(m + 1);
  for(int i = 1; i <= m; i++) {
    for(int j = i; j <= 2 * n; j += m) {
      cnt[i]++;
    }
  }

  dp[0][0] = 1;
  int s = 0;
  for(int i = 1; i <= m; i++) {
    s += cnt[i];
    for(int j = 0; j <= s / 2; j++) {
      for(int k = 0; k <= j && 2 * k <= cnt[i]; k++) {
        long long curr = dp[i - 1][j - k];
        curr = mult(curr, choose(j, k));
        curr = mult(curr, fact[cnt[i]]);
        curr = mult(curr, ifact[cnt[i] - 2 * k]);

        dp[i][j] = add(dp[i][j], curr);
      }
    }
  }

  long long answ = fact[2 * n], ans2 = 0;
  for(int i = 1; i <= n; i++) {
    long long cur = mult(choose(n, i), fact[2 * n - 2 * i]);
    cur = mult(cur, dp[m][i]);

    if(i & 1) {
      answ = sub(answ, cur);
    } else {
      answ = add(answ, cur);
    }
  }
  cout << answ << '\n';
}
 
int main() {
  setIO();
 
  generate();

  auto solve = [&](int test_case)-> void {
    while(test_case--) {
      solve_();
    }
  };
 
  int test_cases = 1; 
  // cin >> test_cases;
  solve(test_cases);
 
  return 0;
}

Compilation message (stderr)

Main.cpp: In function 'void solve_()':
Main.cpp:220:33: warning: unused variable 'ans2' [-Wunused-variable]
  220 |   long long answ = fact[2 * n], ans2 = 0;
      |                                 ^~~~
Main.cpp: In function 'void setIO(std::string)':
Main.cpp:88:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   88 |     freopen((str + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:89:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   89 |     freopen((str + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:91:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   91 |     freopen("input.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:92:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   92 |     freopen("output.txt", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 18 / 18
• Subtask 5: 48 / 48