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  • bzoj1801: [Ahoi2009]chess 中国象棋 dp

    题意:在N行M列的棋盘上,放若干个炮可以是0个,使得没有任何一个炮可以攻击另一个炮。 请问有多少种放置方法,中国像棋中炮的行走方式大家应该很清楚吧.
    题解:dp[i][j][k]表示到了第i行,有j列含1个炮,k列含2个炮,转移随便搞就行了

    /**************************************************************
        Problem: 1801
        User: walfy
        Language: C++
        Result: Accepted
        Time:356 ms
        Memory:11784 kb
    ****************************************************************/
     
    //#pragma GCC optimize(2)
    //#pragma GCC optimize(3)
    //#pragma GCC optimize(4)
    //#pragma GCC optimize("unroll-loops")
    //#pragma comment(linker, "/stack:200000000")
    //#pragma GCC optimize("Ofast,no-stack-protector")
    //#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
    #include<bits/stdc++.h>
    #define fi first
    #define se second
    #define db double
    #define mp make_pair
    #define pb push_back
    #define pi acos(-1.0)
    #define ll long long
    #define vi vector<int>
    #define mod 9999973
    #define ld long double
    #define C 0.5772156649
    #define ls l,m,rt<<1
    #define rs m+1,r,rt<<1|1
    #define pll pair<ll,ll>
    #define pil pair<int,ll>
    #define pli pair<ll,int>
    #define pii pair<int,int>
    //#define cd complex<double>
    #define ull unsigned long long
    #define base 1000000000000000000
    #define Max(a,b) ((a)>(b)?(a):(b))
    #define Min(a,b) ((a)<(b)?(a):(b))
    #define fin freopen("a.txt","r",stdin)
    #define fout freopen("a.txt","w",stdout)
    #define fio ios::sync_with_stdio(false);cin.tie(0)
    template<typename T>
    inline T const& MAX(T const &a,T const &b){return a>b?a:b;}
    template<typename T>
    inline T const& MIN(T const &a,T const &b){return a<b?a:b;}
    inline void add(ll &a,ll b){a+=b;if(a>=mod)a-=mod;}
    inline void sub(ll &a,ll b){a-=b;if(a<0)a+=mod;}
    inline ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
    inline ll qp(ll a,ll b){ll ans=1;while(b){if(b&1)ans=ans*a%mod;a=a*a%mod,b>>=1;}return ans;}
    inline ll qp(ll a,ll b,ll c){ll ans=1;while(b){if(b&1)ans=ans*a%c;a=a*a%c,b>>=1;}return ans;}
     
    using namespace std;
     
    const double eps=1e-8;
    const ll INF=0x3f3f3f3f3f3f3f3f;
    const int N=100+10,maxn=3000000+10,inf=0x3f3f3f3f;
     
    ll c[N][N],dp[N][N][N];
    void init()
    {
        for(int i=0;i<N;i++)
        {
            c[i][0]=c[i][i]=1;
            for(int j=1;j<i;j++)
                c[i][j]=(c[i-1][j]+c[i-1][j-1])%mod;
        }
    }
    int main()
    {
        init();
        int n,m;scanf("%d%d",&n,&m);
        dp[0][0][0]=1;
        for(int i=1;i<=n;i++)
        {
            for(int j=0;j<=m;j++)
            {
                for(int k=0;k<=m;k++)
                {
                    if(j+k>m)continue;
                    int zero=m-j-k;
                    add(dp[i][j][k],dp[i-1][j][k]);
                    if(j+k+1<=m)add(dp[i][j+1][k],dp[i-1][j][k]*c[zero][1]%mod);
                    if(j>=1)add(dp[i][j-1][k+1],dp[i-1][j][k]*c[j][1]%mod);
                    if(j+k+2<=m)add(dp[i][j+2][k],dp[i-1][j][k]*c[zero][2]%mod);
                    if(j>=2)add(dp[i][j-2][k+2],dp[i-1][j][k]*c[j][2]%mod);
                    if(j>=1&&j+k+1<=m)add(dp[i][j][k+1],dp[i-1][j][k]*c[zero][1]%mod*c[j][1]%mod);
                }
            }
        }
        ll ans=0;
        for(int i=0;i<=m;i++)
        {
            for(int j=0;j<=m;j++)
            {
                if(i+j>m)continue;
                add(ans,dp[n][i][j]);
            }
        }
        printf("%lld
    ",ans);
        return 0;
    }
    /********************
     
    ********************/
    
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  • 原文地址:https://www.cnblogs.com/acjiumeng/p/9733159.html
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