HDU 4920 Matrix multiplication

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 typedef long long LL;
 4 const int maxn = 810;
 5 int a[maxn][maxn],b[maxn][maxn],c[maxn][maxn];
 6 int main() {
 7     int n;
 8     while(~scanf("%d",&n)) {
 9         memset(c,0,sizeof c);
10         for(int i = 0; i < n; ++i)
11             for(int j = 0; j < n; ++j) {
12                 scanf("%d",a[i]+j);
13                 a[i][j] %= 3;
14             }
15         for(int i = 0; i < n; ++i)
16             for(int j = 0; j < n; ++j) {
17                 scanf("%d",b[i]+j);
18                 b[i][j] %= 3;
19             }
20         for(int i = 0; i < n; ++i)
21             for(int k = 0; k < n; ++k)
22                 for(int j = 0; j < n; ++j)
23                     c[i][j] += a[i][k]*b[k][j];
24         for(int i = 0; i < n; ++i) {
25             for(int j = 0; j + 1 < n; ++j)
26                 printf("%d ",c[i][j]%3);
27             printf("%d\n",c[i][n-1]%3);
28         }
29     }
30     return 0;
31 }