Submission #2702364

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Source Code Expand

#include "bits/stdc++.h"
using namespace std;
#ifdef _DEBUG
#include "dump.hpp"
#else
#define dump(...)
#endif

//#define int long long
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(c) begin(c),end(c)
const int INF = sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)(1e9) + 7;
template<class T> bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T &a, const T &b) { if (b < a) { a = b; return true; } return false; }

template<int MOD>
struct ModInt {
	static const int kMod = MOD;
	unsigned x;
	ModInt() : x(0) {}
	ModInt(signed sig) { int sigt = sig % kMod; if (sigt < 0) sigt += kMod; x = sigt; }
	ModInt(signed long long sig) { int sigt = sig % kMod; if (sigt < 0) sigt += kMod; x = sigt; }
	int get() const { return (int)x; }

	ModInt &operator+=(ModInt that) { if ((x += that.x) >= kMod) x -= kMod; return *this; }
	ModInt &operator-=(ModInt that) { if ((x += kMod - that.x) >= kMod) x -= kMod; return *this; }
	ModInt &operator*=(ModInt that) { x = (unsigned long long)x * that.x % kMod; return *this; }
	ModInt &operator/=(ModInt that) { return *this *= that.inverse(); }

	ModInt operator+(ModInt that) const { return ModInt(*this) += that; }
	ModInt operator-(ModInt that) const { return ModInt(*this) -= that; }
	ModInt operator*(ModInt that) const { return ModInt(*this) *= that; }
	ModInt operator/(ModInt that) const { return ModInt(*this) /= that; }

	ModInt inverse() const {
		signed a = x, b = kMod, u = 1, v = 0;
		while (b) {
			signed t = a / b;
			a -= t * b; swap(a, b);
			u -= t * v; swap(u, v);
		}
		if (u < 0) u += kMod;
		ModInt res; res.x = (unsigned)u;
		return res;
	}
};
template<int MOD>
ostream &operator << (ostream &os, const ModInt<MOD> &m) { return os << m.x; }
template<int MOD>
istream &operator >> (istream &is, ModInt<MOD> &m) { signed long long s; is >> s; m = ModInt<MOD>(s); return is; };

using mint = ModInt<1000000007>;

mint pow(mint a, unsigned long long k) {
	mint r = 1;
	while (k) {
		if (k & 1) r *= a;
		a *= a;
		k >>= 1;
	}
	return r;
}

vector<mint> fact, factinv;
void precomputeFactorial(int N) {
	N = min(N, mint::kMod - 1);
	fact.resize(N + 1); factinv.resize(N + 1);
	fact[0] = 1;
	rep(i, 1, N + 1) fact[i] = fact[i - 1] * i;
	factinv[N] = fact[N].inverse();
	for (int i = N; i >= 1; i--) factinv[i - 1] = factinv[i] * i;
}
mint combi(int n, int r) {
	if (n >= mint::kMod)
		return combi(n % mint::kMod, r % mint::kMod) * combi(n / mint::kMod, r / mint::kMod);
	return r > n ? 0 : fact[n] * factinv[n - r] * factinv[r];
}


signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int N; cin >> N;
	using P = pair<int, int>;
	vector<P> v;
	vector<int> a(N); rep(i, 0, N) {
		cin >> a[i];
		v.emplace_back(a[i], 0);
	}
	vector<int> b(N); rep(i, 0, N) {
		cin >> b[i];
		v.emplace_back(b[i], 1);
	}
	sort(all(v));

	int q = 0;
	int qs = 0;
	mint ans = 1;

	rep(i, 0, v.size()) {
		if (q == 0) {
			qs = v[i].second;
			q++;
		}
		else {
			if (qs == v[i].second) {
				q++;
			}
			else {
				ans *= q;
				q--;
			}
		}
	}
	cout << ans << endl;

	return 0;
}

Submission Info

Judge Result