P2051-中国象棋

 1 #include <bits/stdc++.h>
 2 #define _for(i,a,b) for(int i = (a);i < b;i ++)
 3 #define _rep(i,a,b) for(int i = (a);i > b;i --)
 4 #define INF 0x3f3f3f3f
 5 #define MOD 9999973
 6 typedef long long ll;
 7 using namespace std;
 8 inline ll read()
 9 {
10     ll ans = 0;
11     char ch = getchar(), last = ‘ ‘;
12     while(!isdigit(ch)) last = ch, ch = getchar();
13     while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - ‘0‘, ch = getchar();
14     if(last == ‘-‘) ans = -ans;
15     return ans;
16 }
17 inline void write(ll x)
18 {
19     if(x < 0) x = -x, putchar(‘-‘);
20     if(x >= 10) write(x / 10);
21     putchar(x % 10 + ‘0‘);
22 }
23 int N,M;
24 ll dp[103][103][103];
25 inline ll C2(ll n)
26 {
27     return ((n*(n-1))/2) % MOD;
28 }
29 int main()
30 {
31     N = read(), M = read();
32     dp[0][0][0] = 1;
33     _for(i,1,N+1)
34         _for(j,0,M+1)
35             _for(k,0,M-j+1)
36             {
37                 ll &t = dp[i][j][k];
38                 t = dp[i-1][j][k];
39                 if(k>=1)    
40                     t += dp[i-1][j+1][k-1]*(j+1);
41                 t %= MOD;
42                 if(j>=1)
43                     t += dp[i-1][j-1][k]*(M-j-k+1);
44                 t %= MOD;
45                 if(k>=2)
46                     t += dp[i-1][j+2][k-2]*C2(j+2);
47                 t %= MOD;
48                 if(k>=1)
49                     t += dp[i-1][j][k-1]*j*(M-j-k+1);
50                 t %= MOD;
51                 if(j>=2)
52                     t += dp[i-1][j-2][k]*C2(M-k-j+2);
53                 t %= MOD;
54             }
55     
56     ll rnt = 0;
57     _for(i,0,M+1)
58         _for(j,0,M+1)
59             rnt += dp[N][i][j],rnt %= MOD;
60     printf("%lld\n",rnt);
61     return 0;
62 }