bzoj1801中国象棋

题目链接

很裸的$dp+$组合计数

注意

注意

注意

$BZOJ$不要用玄学优化

$CE$不管$qwq$

/**************************************************************

    Problem: 1801

    User: zhangheran

    Language: C++

    Result: Accepted

    Time:196 ms

    Memory:11692 kb

****************************************************************/

//#pragma GCC optimize(2)

//#pragma GCC optimize(3)

//#pragma GCC optimize("Ofast")

//#pragma GCC optimize("inline")

//#pragma GCC optimize("-fgcse")

//#pragma GCC optimize("-fgcse-lm")

//#pragma GCC optimize("-fipa-sra")

//#pragma GCC optimize("-ftree-pre")

//#pragma GCC optimize("-ftree-vrp")

//#pragma GCC optimize("-fpeephole2")

//#pragma GCC optimize("-ffast-math")

//#pragma GCC optimize("-fsched-spec")

//#pragma GCC optimize("unroll-loops")

//#pragma GCC optimize("-falign-jumps")

//#pragma GCC optimize("-falign-loops")

//#pragma GCC optimize("-falign-labels")

//#pragma GCC optimize("-fdevirtualize")

//#pragma GCC optimize("-fcaller-saves")

//#pragma GCC optimize("-fcrossjumping")

//#pragma GCC optimize("-fthread-jumps")

//#pragma GCC optimize("-funroll-loops")

//#pragma GCC optimize("-fwhole-program")

//#pragma GCC optimize("-freorder-blocks")

//#pragma GCC optimize("-fschedule-insns")

//#pragma GCC optimize("inline-functions")

//#pragma GCC optimize("-ftree-tail-merge")

//#pragma GCC optimize("-fschedule-insns2")

//#pragma GCC optimize("-fstrict-aliasing")

//#pragma GCC optimize("-fstrict-overflow")

//#pragma GCC optimize("-falign-functions")

//#pragma GCC optimize("-fcse-skip-blocks")

//#pragma GCC optimize("-fcse-follow-jumps")

//#pragma GCC optimize("-fsched-interblock")

//#pragma GCC optimize("-fpartial-inlining")

//#pragma GCC optimize("no-stack-protector")

//#pragma GCC optimize("-freorder-functions")

//#pragma GCC optimize("-findirect-inlining")

//#pragma GCC optimize("-fhoist-adjacent-loads")

//#pragma GCC optimize("-frerun-cse-after-loop")

//#pragma GCC optimize("inline-small-functions")

//#pragma GCC optimize("-finline-small-functions")

//#pragma GCC optimize("-ftree-switch-conversion")

//#pragma GCC optimize("-foptimize-sibling-calls")

//#pragma GCC optimize("-fexpensive-optimizations")

//#pragma GCC optimize("-funsafe-loop-optimizations")

//#pragma GCC optimize("inline-functions-called-once")

//#pragma GCC optimize("-fdelete-null-pointer-checks")

//#include"suqingnian.h"

#include<iostream>

#include<cstdio>

#include<algorithm>

using namespace std;

const int mod=;

long long dp[][][];

int n,m;long long ans;

long long calc(long long xx) {return xx*(xx-)/;}

int main()

{

    scanf("%d%d",&n,&m);

    dp[][][]=;

    for(int i=;i<n;i++)

      for(int j=;j<=m;j++)

        for(int k=;k<=m-j;k++)

        if(dp[i][j][k]){

        if(j->=)  dp[i+][j-][k+]=(dp[i+][j-][k+]+dp[i][j][k]*calc(j))%mod;

        if(j->=)  dp[i+][j-][k+]=(dp[i+][j-][k+]+dp[i][j][k]*j)%mod;

            dp[i+][j][k]=(dp[i+][j][k]+dp[i][j][k])%mod,

            dp[i+][j][k+]=(dp[i+][j][k+]+dp[i][j][k]*(m-j-k)*j)%mod,

            dp[i+][j+][k]=(dp[i+][j+][k]+dp[i][j][k]*(m-j-k))%mod,

            dp[i+][j+][k]=(dp[i+][j+][k]+dp[i][j][k]*calc(m-j-k))%mod;

//      printf("%d %d %d %d\n",i,j,k,dp[i][j][k]);

    }

    for(int i=;i<=m;i++)

      for(int j=;j<=m-i;j++)

//      printf("%lld ",dp[n][i][j]);

        ans=(ans+dp[n][i][j])%mod;

    printf("%lld\n",ans%mod);

}