[luogu P3390] 【模板】矩阵快速幂

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题目

https://www.luogu.org/problemnew/show/P3390#sub

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解题思路

这道题就是矩阵乘法的模板题，注意一下 $f[i][i]=1$这个初始化就可以了。

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代码

#include<cstdio>
#include<iostream>
#include<cstring>
#define WYC 1000000007
#define LL long long
#define rep(i,x,y) for(register long long i=x;i<=y;i++)
using namespace std; 
LL n,kk,f[1001][1001],a[1001][1001],c[1001][1001]; 
inline LL read()
{
	LL p=0; char c=getchar();
	while (!isdigit(c)) c=getchar(); 
	while (isdigit(c)) p=(p<<3)+(p<<1)+c-48,c=getchar(); 
	return p; 
}
void mull()
{
    memset(c,0,sizeof(c)); 
    rep(i,1,n) rep(j,1,n) rep(k,1,n) c[i][j]=c[i][j]%WYC+a[i][k]*a[k][j]%WYC; 
    memcpy(a,c,sizeof(c)); 
}
void mul()
{
    memset(c,0,sizeof(c)); 
    rep(i,1,n) rep(j,1,n) rep(k,1,n) c[i][j]=c[i][j]%WYC+f[i][k]*a[k][j]%WYC; 
    memcpy(f,c,sizeof(c));
}
int main()
{
    n=read(),kk=read(); 
    rep(i,1,n) rep(j,1,n)  a[i][j]=read(),f[i][i]=1; 
    for(;kk;mull(),kk>>=1) if (kk&1) mul();
    rep(i,1,n) {rep(j,1,n) printf("%lld ",f[i][j]%WYC); putchar(10);}
}