Submission #122326

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Source Code Expand

#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <climits>
#include <cfloat>
#include <functional>
using namespace std;

class Mod
{
    static const int MOD = 1000000007;
    long long a;
public:
    Mod(){
        a = 0;
    }
    Mod(long long x){
        a = (x % MOD + MOD) % MOD;
    }
    const Mod operator+(const Mod& x) const{
        return Mod(a + x.a);
    }
    const Mod operator-(const Mod& x) const{
        return Mod(a - x.a);
    }
    const Mod operator*(const Mod& x) const{
        return Mod(a * x.a);
    }
    const Mod operator/(const Mod& x) const{ // フェルマーの小定理、x.aとMODが互いに素な場合のみ有効
        int b = MOD - 2;
        long long c = x.a;
        long long ret = 1;
        while(b > 0){
            if(b & 1){
                ret *= c;
                ret %= MOD;
            }
            c *= c;
            c %= MOD;
            b >>= 1;
        }
        return Mod(a * ret);
    }
    long long getValue(){
        return a;
    }
};

Mod combination(int n, int r)
{
    if(n < r)
        return 0;
    if(n-r < r)
        r = n-r;
    Mod ret = 1;
    for(int i=0; i<r; i++){
        ret = ret * (n--);
        ret = ret / (i+1);
    }
    return ret;
}

int main()
{
    int h, w, hr, wr, d, l;
    cin >> h >> w >> hr >> wr >> d >> l;

    Mod ret = 0;
    for(int i=0; i<4; ++i){
        for(int j=0; j<4; ++j){
            bitset<2> bs1(i), bs2(j);
            int y = hr - bs1.count();
            int x = wr - bs2.count();
            if(y <= 0 || x <= 0)
                continue;
            if((bs1.count() + bs2.count()) % 2 == 0)
                ret = ret + combination(y * x, d + l);
            else
                ret = ret - combination(y * x, d + l);
        }
    }

    ret = ret * (h - hr + 1) * (w - wr + 1);
    ret = ret * combination(d + l, d);

    cout << ret.getValue() << endl;

    return 0;
}

Submission Info

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