不会把还有人不知道矩阵乘法

#include<bits/stdc++.h>
#define int long long//记得开longlong
using namespace std;
const int N = 600, M = 1e9 + 7;
int a[N][N], b[N][N];
inline int max(int x, int y){return x > y ? x : y;}
inline int min(int x, int y){return x > y ? y : x;}
inline int read(){
	int x = 0, f = 1; char c = getchar();
	while (!isdigit(c)){if (c == '-') f = -1; c = getchar();}
	while (isdigit(c)){x = (x << 3) + (x << 1) + (c ^ 48); c = getchar(); }
	return x * f;
}
inline void write(int x){
	if (x < 0) {x = ~(x - 1); putchar('-');}
	if (x > 9) write(x / 10);
	putchar(x % 10 ^ 48);
}
signed main(){
	int n = read(), p = read(), m = read();
	for (int i = 1; i <= n; i ++)
	    for (int j = 1; j <= p; j ++)
	        a[i][j] = (read() + M) % M;//记得取模
	for (int i = 1; i <= p; i ++)
	    for (int j = 1; j <= m; j ++)
	        b[i][j] = (read() + M) % M;//记得取模
	for (int i = 1; i <= n; i ++){
	    for (int j = 1; j <= m; j ++){
	    	int sum = M;
	    	for (int k = 1; k <= p; k ++)
	    	    sum = (sum + a[i][k] * b[k][j]) % M;
	    	write(sum % M);putchar(' ');
		}
		puts("");
	}
	return 0;
}