原题http://acm.hdu.edu.cn/showproblem.php?pid=4920

Matrix multiplication

Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 131072/131072 K (Java/Others)
Total Submission(s): 848 Accepted Submission(s): 339

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

Sample Output

0
0 1
2 1

Author Xiaoxu Guo (ftiasch)

Source 2014 Multi-University Training Contest 5

Recommend We have carefully selected several similar problems for you: 4919 4918 4917 4916 4915

//开始的时候还以为这题要用到什么高深的算法。后来发现很多人过了，估计就是小技巧了
//首先。乘法的运算时间要比加法多。所以能避免乘法，尽量优化掉。
//经过这题，发现C++比G++跑的要更快，同样的代码差了差不多0.4秒。比赛的时候就是由于交了G++T了好多次
//最后，说一句，骚年，虽然暴力不是万能的。但是没有加上小技巧的暴力是万万不能的。
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                  using namespace std; #define Max 800 + 5 int a[Max][Max]; int b[Max][Max]; int c[Max][Max]; int main(){ int n,i,j; while(~scanf("%d",&n)){ memset(a,0,sizeof(a)); memset(b,0,sizeof(b)); memset(c,0,sizeof(c)); for(i=0;i

HDU4920妥妥的暴力

Matrix multiplication