題目

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

解題思路

這道題就是矩陣乘法的模板題，注意一下 $f\left[i\right]\left[i\right]$

程式碼

#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);}
}