Submission #122359

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Source Code Expand

#define _CRT_SECURE_NO_WARNINGS
#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <list>
#include <cassert>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#if defined(_MSC_VER) || __cplusplus > 199711L
#define aut(r,v) auto r = (v)
#else
#define aut(r,v) typeof(v) r = (v)
#endif
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
#define EPS 1e-9
using namespace std;
typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii;
typedef long long ll; typedef vector<long long> vl; typedef pair<long long,long long> pll; typedef vector<pair<long long,long long> > vpll;
typedef vector<string> vs; typedef long double ld;

template<int MOD>
struct ModInt {
	unsigned x;
	ModInt(): x(0) { }
	ModInt(signed sig) { if((x = sig % MOD + MOD) >= MOD) x -= MOD; }
	//inverseを使う場合これが必要！！！！！。llを使う場合は残しとけ！暗黙に変換されて壊れる！！！！
	ModInt(signed long long sig) { if((x = sig % MOD + MOD) >= MOD) x -= MOD; }
	unsigned get() const { return x; }
	
	ModInt &operator+=(ModInt that) { if((x += that.x) >= MOD) x -= MOD; return *this; }
	ModInt &operator-=(ModInt that) { if((x += MOD - that.x) >= MOD) x -= MOD; return *this; }
	ModInt &operator*=(ModInt that) { x = (unsigned long long)x * that.x % MOD; 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 {
		long long a = x, b = MOD, u = 1, v = 0;
		while(b) {
			long long t = a / b;
			a -= t * b; std::swap(a, b);
			u -= t * v; std::swap(u, v);
		}
		return ModInt(u);
	}
};
template<unsigned MOD> ModInt<MOD> operator^(ModInt<MOD> a, unsigned long long k) {
	ModInt<MOD> r = 1;
	while(k) {
		if(k & 1) r *= a;
		a *= a;
		k >>= 1;
	}
	return r;
}

typedef ModInt<1000000007> mint;

vector<mint> fact, factinv;
void nCr_computeFactinv(const int N) {
	fact.resize(N+1); factinv.resize(N+1);
	fact[0] = 1;
	rer(i, 1, N) 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 nCr(int n, int r) {
	return r > n ? 0 : fact[n] * factinv[n-r] * factinv[r];
}


int W, H, X, Y, D, L;
int main() {
	cin >> W >> H >> X >> Y >> D >> L;
	//4辺に対してOKなものをS(i)とすると
	//答え = ∩ S(i)
	//包除原理で
	nCr_computeFactinv(X * Y);
	mint r;
	rep(mask, 1<<4) {
		int w = X, h = Y;
		if(mask >> 0 & 1) w --;
		if(mask >> 1 & 1) w --;
		if(mask >> 2 & 1) h --;
		if(mask >> 3 & 1) h --;
		if(w <= 0 || h <= 0) continue;
		bool parity = false;
		rep(i, 4) if(mask >> i & 1) parity ^= 1;
		mint x = nCr(w * h, D) * nCr(w * h - D, L);
		if(!parity) r += x; else r -= x;
	}
	r *= W-X+1;
	r *= H-Y+1;
	cout << r.get() << endl;
	return 0;
}

Submission Info

Judge Result