Matrix multiplication
Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 131072/131072 K (Java/Others)
Total Submission(s): 3841 Accepted Submission(s): 1577
Problem Description
Given two matrices A and B of size n×n, find the product of them.
bobo hates big integers. So you are only asked to find the result modulo 3.
Input
The input consists of several tests. For each tests:
The first line contains n (1≤n≤800). Each of the following n lines contain n integers -- the description of the matrix A. The j-th integer in the i-th line equals A
ij. The next n lines describe the matrix B in similar format (0≤A
ij,B
ij≤10
9).
Output
For each tests:
Print n lines. Each of them contain n integers -- the matrix A×B in similar format.
Sample Input
1
0
1
2
0 1
2 3
4 5
6 7
Sample Output
0
0 1
2 1
//一直超时，明天再看
#include<stdio.h>
#include<string.h>
#include<math.h>
#include<algorithm>
using namespace std;
int a[810][810];
int b[810][810];
int c[810][810];
int main()
{
int n,i,j,k;
while(scanf("%d",&n)!=EOF)
{
for(i=1;i<=n;i++)
{
for(j=1;j<=n;j++)
{
scanf("%d",&a[i][j]);
a[i][j]%=3;
}
}
for(i=1;i<=n;i++)
{
for(j=1;j<=n;j++)
{
scanf("%d",&b[i][j]);
b[i][j]%=3;
}
}
memset(c,0,sizeof(c));
for(i=1;i<=n;i++)
{
for(j=1;j<=n;j++)
{
for(k=1;k<=n;k++)
{
c[i][j]=(c[i][j]+a[i][k]*b[k][j]);
}
}
}
for(i=1;i<=n;i++)
{
for(j=1;j<n;j++)
printf("%d ",a[i][j]%3);
printf("%d\n",a[i][n]%3);
}
}
return 0;
}
