luogu题解 P1707 【刷题比赛】矩阵加速递推

  • 题目链接:

    https://www.luogu.org/problemnew/show/P1707

  • 分析:

    洛谷的一道原创题,对于练习矩阵加速递推非常不错。

    首先我们看一下递推式:

    (a[k+2]=p*a[k+1]+q*a[k]+b[k+1]+c[k+1]+r*k^2+t*k+1;)
    (b[k+2]=u*b[k+1]+v*b[k]+a[k+1]+c[k+1]+w^k;)
    (c[k+2]=x*c[k+1]+y*c[k]+a[k+1]+b[k+1]+z^k+k+2;)

    有点吓人,我想在做这道题的人都能对类似(p*a[k+1])都能进行转移矩阵的构建,主要我们处理后面这些。

    (f[k]=k^2)

    (f[k+1]=(k+1)^2=f[k]+2*k+1;)

    (g[k]=k)

    (g[k+1]=g[k]+1;)

    (h[k]=w^k)

    (h[k+1]=h[k]*w;)

    (p[k]=z^k)

    (p[k+1]=p[k]*z;)

    (q[k]=x*k)

    (q[k+1]=q[k]+x;)

    然后就全都转化成线性递推,搞一个状态矩阵:

    (ans={a2,a1,b2,b1,c2,c1,f[k],g[k],h[k],p[k],k,1})

    转移矩阵:

    ({p,q,1,0,1,0,r,0,0,0,t,1})

    ({1,0,0,0,0,0,0,0,0,0,0,0})

    ({1,0,u,v,1,0,0,0,1,0,0,0})

    ({0,0,1,0,0,0,0,0,0,0,0,0})

    ({1,0,1,0,x,y,0,0,0,1,1,2})

    ({0,0,0,0,1,0,0,0,0,0,0,0})

    ({0,0,0,0,0,0,1,0,0,0,2,1})

    ({0,0,0,0,0,0,0,1,0,0,0,1})

    ({0,0,0,0,0,0,0,0,w,0,0,0})

    ({0,0,0,0,0,0,0,0,0,z,0,0})

    ({0,0,0,0,0,0,0,0,0,0,1,1})

    ({0,0,0,0,0,0,0,0,0,0,0,1})

    好了,你就可以开始了。

    然而有个很毒瘤的地方:你可能需要快速乘

    然后一开始我不知道在这里卡了好久

    我只想说

    这题对于一个蒟蒻而言太毒瘤了!!!

  • 代码:

#include <iostream>
#include <cstdio> 
#include <cstdlib>
#include <cstring>
#include <cctype>
#include <algorithm>
#define ll long long   
using namespace std;
const int maxn=17;
ll N,k;
int p,q,r,t,u,v,w,x,y,z;
ll q_mul(ll a,ll b)
{
   ll ans=0;
   while(b)
  {
   if(b&1) ans=(ans+a)%k;
   a=(a+a)%k;
   b>>=1;
  }
   return ans;
}
struct Matrix{
	int n,m;
	ll ma[maxn][maxn];
	Matrix(int _n){n=m=_n;memset(ma,0,sizeof(ma));for(register int i=1;i<=n;i++)ma[i][i]=1;}
	Matrix(int _n,int _m){n=_n,m=_m;memset(ma,0,sizeof(ma));}
	Matrix(){;}
	Matrix operator *(const Matrix &b)const{
		Matrix ans=Matrix(n,b.m);
		for(register int i=1;i<=n;i++){
			for(register int j=1;j<=b.m;j++){
				ll tmp=0;
				for(register int o=1;o<=m;o++){
					tmp+=q_mul(ma[i][o],b.ma[o][j]);//(ma[i][o]%k*b.ma[o][j]%k)%k;
					//if(tmp>1000000)tmp=tmp%k;
				}
				ans.ma[i][j]=tmp%k;
			}
		}
		return ans;
	}
	Matrix operator ^(const ll& C)const {
		ll c=C;
		Matrix res=*this;
		Matrix ans=Matrix(n);
		while(c){
			if(c&1)ans=ans*res;
			res=res*res;
			c=c>>1;
		}
		return ans;
	} 
};
void print(ll x)//输出
{
    if(x<0)
    {
        x =-x;
        putchar('-');
    }
     if(x>9) print(x/10);
    putchar(x%10+'0');
}
int main(){
	scanf("%lld %lld %d %d %d %d %d %d %d %d %d %d",&N,&k,&p,&q,&r,&t,&u,&v,&w,&x,&y,&z);
	Matrix ans=Matrix(12,1);
    ans.ma[1][1]=3,ans.ma[2][1]=1,ans.ma[3][1]=3,ans.ma[4][1]=1,ans.ma[5][1]=3,ans.ma[6][1]=1;
	ans.ma[7][1]=1,ans.ma[8][1]=1,ans.ma[9][1]=w,ans.ma[10][1]=z,ans.ma[11][1]=1,ans.ma[12][1]=1;
	
	Matrix A=Matrix(12,12);
	A.ma[1][1]=p,A.ma[1][2]=q,A.ma[1][3]=1,A.ma[1][5]=1,A.ma[1][7]=r,A.ma[1][11]=t,A.ma[1][12]=1;
	A.ma[2][1]=1;
	A.ma[3][1]=1,A.ma[3][3]=u,A.ma[3][4]=v,A.ma[3][5]=1,A.ma[3][9]=1;
	A.ma[4][3]=1;
	A.ma[5][1]=1,A.ma[5][3]=1,A.ma[5][5]=x,A.ma[5][6]=y,A.ma[5][10]=1,A.ma[5][11]=1,A.ma[5][12]=2;
	A.ma[6][5]=1;
	A.ma[7][7]=1,A.ma[7][11]=2,A.ma[7][12]=1;
	A.ma[8][8]=A.ma[8][12]=1;
	A.ma[9][9]=w,A.ma[10][10]=z,A.ma[11][11]=A.ma[11][12]=1,A.ma[12][12]=1;
	A=A^(N-2);
	ans=A*ans;
	printf("nodgd %lld
Ciocio %lld
Nicole %lld",ans.ma[1][1],ans.ma[3][1],ans.ma[5][1]);
	return 0;
}
原文地址:https://www.cnblogs.com/Rye-Catcher/p/9089459.html