给定两个矩阵A和B,要求你计算它们的乘积矩阵AB。需要注意的是,只有规模匹配的矩阵才可以相乘。即若A有Ra行、Ca列,B有Rb行、Cb列,则只有Ca与Rb相等时,两个矩阵才能相乘。
输入格式:
输入先后给出两个矩阵A和B。对于每个
矩阵,首先在一行中给出其行数R和列数C,随后R行,每行给出C个整数,以1个空格分隔,且行首尾没有多余的空格。输入保证两个矩阵的R和C都是正数,并且所有整数的绝对值不超过100。
输出格式:
若输入的两个矩阵的规模是匹配的,则按照输入的格式输出乘积矩阵AB,否则输出“Error: Ca != Rb”,其中Ca是A的列数,Rb是B的行数。
输入样例1:
2 3
1 2 3
4 5 6
3 4
7 8 9 0
-1 -2 -3 -4
5 6 7 8
输出样例1:
2 4
20 22 24 16
53 58 63 28
输入样例2:
3 2
38 26
43 -5
0 17
3 2
-11 57
99 68
81 72
输出样例2:
Error: 2 != 3
Java版本,最后一个测试点超时:
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int Ra = scanner.nextInt();
int Ca = scanner.nextInt();
int[][] A = new int[Ra][Ca];
// input matrixA
for (int i = 0; i < Ra; i++) {
for (int j = 0; j < Ca; j++) {
A[i][j] = scanner.nextInt();
}
}
int Rb = scanner.nextInt();
if (Ca == Rb) {
int Cb = scanner.nextInt();
int[][] B = new int[Rb][Cb];
// input matrixB
for (int i = 0; i < Rb; i++) {
for (int j = 0; j < Cb; j++) {
B[i][j] = scanner.nextInt();
}
}
System.out.println(Ra + " " + Cb);
int[][] C = new int[Ra][Cb];
for (int i = 0; i < Ra; i++) {
for (int j = 0; j < Cb; j++) {
for (int k = 0; k < Ca; k++) {
C[i][j] += A[i][k] * B[k][j];
}
System.out.print(C[i][j]);
if (j != Cb-1) {
System.out.print(" ");
}
}
System.out.println();
}
} else {
System.out.println("Error: " + Ca + " != " + Rb);
}
}
}
C语言版,顺利通过,原理相同:
#include <stdio.h>
int main()
{
int A[200][200], B[200][200];
int Ra, Ca, Rb, Cb;
scanf("%d %d", &Ra, &Ca);
for (int i = 0; i < Ra; i++) {
for (int j = 0; j < Ca; j++) {
scanf("%d", &A[i][j]);
}
}
scanf("%d %d", &Rb, &Cb);
for (int i = 0; i < Rb; i++) {
for (int j = 0; j < Cb; j++) {
scanf("%d", &B[i][j]);
}
}
if (Ca == Rb)
{
printf("%d %d\n", Ra, Cb);
//int C[200][200];
for (int i = 0; i < Ra; i++)
{
for (int j = 0; j < Cb; j++)
{
int sum = 0;
for (int k = 0; k < Ca; k++)
{
sum += A[i][k] * B[k][j];
}
printf("%d", sum);
if (j != Cb-1)
{
printf(" ");
}
}
printf("\n");
}
}
else {
printf("Error: %d != %d\n", Ca, Rb);
}
return 0;
}