#define DEBUG 0
#include <bits/stdc++.h>
using namespace std;
#if DEBUG
// basic debugging macros
int __i__,__j__;
#define printLine(l) for(__i__=0;__i__<l;__i__++){cout<<"-";}cout<<endl
#define printLine2(l,c) for(__i__=0;__i__<l;__i__++){cout<<c;}cout<<endl
#define printVar(n) cout<<#n<<": "<<n<<endl
#define printArr(a,l) cout<<#a<<": ";for(__i__=0;__i__<l;__i__++){cout<<a[__i__]<<" ";}cout<<endl
#define print2dArr(a,r,c) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<a[__i__][__j__]<<" ";}cout<<endl;}
#define print2dArr2(a,r,c,l) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<setw(l)<<setfill(' ')<<a[__i__][__j__]<<" ";}cout<<endl;}
// advanced debugging class
// debug 1,2,'A',"test";
class _Debug {
public:
template<typename T>
_Debug& operator,(T val) {
cout << val << endl;
return *this;
}
};
#define debug _Debug(),
#else
#define printLine(l)
#define printLine2(l,c)
#define printVar(n)
#define printArr(a,l)
#define print2dArr(a,r,c)
#define print2dArr2(a,r,c,l)
#define debug
#endif
// define
#define MAX_VAL 999999999
#define MAX_VAL_2 999999999999999999LL
#define EPS 1e-6
#define mp make_pair
#define pb push_back
// typedef
typedef unsigned int UI;
typedef long long int LLI;
typedef unsigned long long int ULLI;
typedef unsigned short int US;
typedef pair<int,int> pii;
typedef pair<LLI,LLI> plli;
typedef vector<int> vi;
typedef vector<LLI> vlli;
typedef vector<pii> vpii;
typedef vector<plli> vplli;
// ---------- END OF TEMPLATE ----------
#define MOD 1000000007
LLI inv(LLI n) {
int e = MOD-2;
LLI r = 1;
while (e > 0) {
if (e & 1) r *= n,r %= MOD;
e >>= 1;
n *= n,n %= MOD;
}
return r;
}
LLI fact[3001],invf[3001],invpow2[6001];
LLI dp[3001][3001];
LLI choose(LLI n,LLI k) {
return (fact[n]*((invf[k]*invf[n-k]) % MOD)) % MOD;
}
int main() {
int H,W;
cin >> H >> W;
int i,j;
LLI ans = 0;
fact[0] = invf[0] = 1;
for (i = 1; i <= max(H,W); i++) fact[i] = (fact[i-1]*i) % MOD,invf[i] = inv(fact[i]);
invpow2[0] = 1;
for (i = 1; i <= H+W; i++) invpow2[i] = (invpow2[i-1]*inv(2)) % MOD;
for (i = 0; i <= W; i++) dp[0][i] = 1;
for (i = 1; i <= H; i++) {
dp[i][0] = 1;
for (j = 1; j <= W; j++) dp[i][j] = (dp[i-1][j]+4*j*dp[i-1][j-1]) % MOD;
}
for (i = 0; i <= H; i++) {
for (j = 0; j <= W; j++) {
if ((i+2*j <= H) && (j+2*i <= W)) {
LLI x = (((choose(H,i)*choose(W,2*i)) % MOD)*fact[2*i]) % MOD;
LLI y = (((choose(W-2*i,j)*choose(H-i,2*j)) % MOD)*fact[2*j]) % MOD;
ans += ((x*y) % MOD)*((dp[H-i-2*j][W-j-2*i]*invpow2[i+j]) % MOD);
ans %= MOD;
}
}
}
cout << (ans+MOD-1) % MOD << endl;
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
376 KB |
Output is correct |
2 |
Correct |
2 ms |
376 KB |
Output is correct |
3 |
Correct |
2 ms |
504 KB |
Output is correct |
4 |
Correct |
3 ms |
1272 KB |
Output is correct |
5 |
Correct |
2 ms |
760 KB |
Output is correct |
6 |
Correct |
3 ms |
1400 KB |
Output is correct |
7 |
Correct |
3 ms |
888 KB |
Output is correct |
8 |
Correct |
3 ms |
1528 KB |
Output is correct |
9 |
Correct |
2 ms |
888 KB |
Output is correct |
10 |
Correct |
4 ms |
1784 KB |
Output is correct |
11 |
Correct |
2 ms |
376 KB |
Output is correct |
12 |
Correct |
4 ms |
2296 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
2 ms |
376 KB |
Output is correct |
2 |
Correct |
2 ms |
376 KB |
Output is correct |
3 |
Correct |
2 ms |
504 KB |
Output is correct |
4 |
Correct |
3 ms |
1272 KB |
Output is correct |
5 |
Correct |
2 ms |
760 KB |
Output is correct |
6 |
Correct |
3 ms |
1400 KB |
Output is correct |
7 |
Correct |
3 ms |
888 KB |
Output is correct |
8 |
Correct |
3 ms |
1528 KB |
Output is correct |
9 |
Correct |
2 ms |
888 KB |
Output is correct |
10 |
Correct |
4 ms |
1784 KB |
Output is correct |
11 |
Correct |
2 ms |
376 KB |
Output is correct |
12 |
Correct |
4 ms |
2296 KB |
Output is correct |
13 |
Correct |
3 ms |
376 KB |
Output is correct |
14 |
Correct |
10 ms |
9720 KB |
Output is correct |
15 |
Correct |
144 ms |
55288 KB |
Output is correct |
16 |
Correct |
7 ms |
4088 KB |
Output is correct |
17 |
Correct |
24 ms |
12924 KB |
Output is correct |
18 |
Correct |
39 ms |
17144 KB |
Output is correct |
19 |
Correct |
165 ms |
63156 KB |
Output is correct |
20 |
Correct |
132 ms |
50996 KB |
Output is correct |
21 |
Correct |
83 ms |
34040 KB |
Output is correct |
22 |
Correct |
87 ms |
35576 KB |
Output is correct |
23 |
Correct |
35 ms |
27128 KB |
Output is correct |
24 |
Correct |
240 ms |
71032 KB |
Output is correct |
25 |
Correct |
181 ms |
61440 KB |
Output is correct |
26 |
Correct |
204 ms |
66680 KB |
Output is correct |
27 |
Correct |
216 ms |
68984 KB |
Output is correct |