BZOJ 4806 炮

同BZOJ1801。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define mod 999983
using namespace std;
long long n,m,dp[105][105][105];
long long calc(long long x) {return (x*(x-1)/2)%mod;}
int main()
{
    scanf("%lld%lld",&n,&m);
    dp[0][0][0]=1;
    for (long long i=1;i<=n;i++)
        for (long long j=0;j<=m;j++)
            for (long long k=0;k<=m-j;k++)
            {
                dp[i][j][k]+=dp[i-1][j][k];dp[i][j][k]%=mod;
                if (j) dp[i][j][k]+=dp[i-1][j-1][k]*(m-j-k+1)%mod;dp[i][j][k]%=mod;
                if ((k) && (j<=m-1)) dp[i][j][k]+=dp[i-1][j+1][k-1]*(j+1)%mod;dp[i][j][k]%=mod;
                if (j>=2) dp[i][j][k]+=dp[i-1][j-2][k]*calc(m-j-k+2)%mod;dp[i][j][k]%=mod;
                if (k) dp[i][j][k]+=dp[i-1][j][k-1]*(j*(m-j-k+1)%mod)%mod;dp[i][j][k]%=mod;
                if ((k>=2) && (j<=m-2)) dp[i][j][k]+=dp[i-1][j+2][k-2]*calc(j+2)%mod;
            }
    long long ans=0;
    for (int i=0;i<=m;i++)
        for (int j=0;j<=m-i;j++)
            ans=(ans+dp[n][i][j])%mod;
    printf("%lld\n",ans);
    return 0;
}