标签：des style blog http color java os io
Matrix multiplication
Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 131072/131072 K (Java/Others)
Total Submission(s): 2143 Accepted Submission(s): 967Problem DescriptionGiven 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.
InputThe 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 Aij. The next n lines describe the matrix B in similar format (0≤Aij,Bij≤109).
OutputFor each tests:
Print n lines. Each of them contain n integers -- the matrix A×B in similar format.
Sample Input10120 12 34 56 7Sample Output00 12 1
请看完这篇博文，看完就去AC吧。加了输入优化，效果并不明显。
1 /*************************************************************************
2 > File Name: 1010.cpp
3 > Author: Stomach_ache
4 > Mail: sudaweitong@gmail.com
5 > Created Time: 2014年08月05日 星期二 19时22分23秒
6 > Propose:
7 ************************************************************************/
8
9 #include <cmath>
10 #include <string>
11 #include <cstdio>
12 #include <fstream>
13 #include <cstring>
14 #include <iostream>
15 #include <algorithm>
16 using namespace std;
17
18 int n;
19 int a[802][802], b[802][802], c[802][802];
20
21 int read() {
22 int res = 0;
23 char c = ‘ ‘;
24 while (c < ‘0‘ || c > ‘9‘) c = getchar();
25 while (c >= ‘0‘ && c <= ‘9‘) res += c - ‘0‘, c = getchar();
26 return res%3;
27 }
28
29 int main(void) {
30 while (~scanf("%d", &n)) {
31 for (int i = 0; i < n; i++)
32 for (int j = 0; j < n; j++)
33 a[i][j] = read();
34 for (int i = 0; i < n; i++)
35 for (int j = 0; j < n; j++)
36 b[i][j] = read();
37 memset(c, 0, sizeof(c));
38 for (int i = 0; i < n; i++) {
39 for (int k = 0; k < n; k++) {
40 for (int j = 0; j < n; j++) {
41 c[i][j] += a[i][k] * b[k][j]; //注意这里的循环顺序
42 }
43 }
44 }
45 for (int i = 0; i < n; i++)
46 for (int j = 0; j < n; j++)
47 printf("%d%c", c[i][j]%3, j == n-1 ? ‘\n‘ : ‘ ‘);
48 }
49 return 0;
50 }
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标签：des style blog http color java os io
原文地址：http://www.cnblogs.com/Stomach-ache/p/3899133.html
