Submission #339259

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Source Code Expand

#include<iostream>
#include<stdio.h>
#include<algorithm>
using namespace std;
#define rep(i,a,b) for(auto (i)=(a);(i)<(b);(i)++)
#define LL long long
#define MOD 1000000007
LL comb[1000][1000];
LL uniq[31][31];
int r, c, x, y, d, l, xy;
void init(){
	comb[0][0] = 1;
	rep(i, 1ll, xy+1){
		comb[i][0] = comb[i][i] = 1;
	}
	rep(i, 2, xy+1){
		rep(j, 1, i){
			comb[i][j] = (comb[i - 1][j - 1] + comb[i - 1][j]) % MOD;
		}
	}
	rep(i, 0, 31){
		rep(j, 0, 31){
			uniq[i][j] = -1;
		}
	}

}
LL recall(int n,int m){
	LL nm = n*m;
	if (uniq[n][m] >= 0)
		return(uniq[n][m]);
	if (nm < d + l)
		return(uniq[n][m] = 0);
	LL c = (comb[nm][d] * comb[nm - d][l]) % MOD;
	
	LL sum = 0, h, w;
	rep(i, 1, n+1){
		h = n - i + 1;
		rep(j, 1, m+1){
			w = m - j + 1;
			if ((i != n) || (j != m))
				sum = (sum + h * w * recall(i, j)%MOD) % MOD;
		}
	}
	return(uniq[n][m] = (c - sum + MOD) % MOD);
}


int main(void){	
	cin >> r >> c >> x >> y >> d >> l;
	xy = x*y;
	init();
	cout << (recall(x, y)*(r - x + 1)*(c - y + 1)) % MOD << endl;
}

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