给定两个矩阵AAA和BBB,要求你计算它们的乘积矩阵ABABAB。需要注意的是,只有规模匹配的矩阵才可以相乘。即若AAA有RaR_aRa行、CaC_aCa列,BBB有RbR_bRb行、CbC_bCb列,则只有CaC_aCa与RbR_bRb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AAA和BBB。对于每个矩阵,首先在一行中给出其行数RRR和列数CCC,随后RRR行,每行给出CCC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RRR和CCC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ABABAB,否则输出Error: Ca != Rb
,其中Ca
是AAA的列数,Rb
是BBB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
最后测试点一个超时
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.StringTokenizer;
//** Class for buffered reading int and double values *//*
class Reader {
static BufferedReader reader;
static StringTokenizer tokenizer;
// ** call this method to initialize reader for InputStream *//*
static void init(InputStream input) {
reader = new BufferedReader(new InputStreamReader(input));
tokenizer = new StringTokenizer("");
}
// ** get next word *//*
static String next() throws IOException {
while (!tokenizer.hasMoreTokens()) {
// TODO add check for eof if necessary
tokenizer = new StringTokenizer(reader.readLine());
}
return tokenizer.nextToken();
}
static boolean hasNext()throws IOException {
return tokenizer.hasMoreTokens();
}
static String nextLine() throws IOException{
return reader.readLine();
}
static char nextChar() throws IOException{
return next().charAt(0);
}
static int nextInt() throws IOException {
return Integer.parseInt(next());
}
static float nextFloat() throws IOException {
return Float.parseFloat(next());
}
}
public class Main {
public static void main(String[] args) throws IOException {
Reader.init(System.in);
int Ra = Reader.nextInt();
int Ca = Reader.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] = Reader.nextInt();
}
}
int Rb = Reader.nextInt();
if (Ca == Rb) {
int Cb = Reader.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] = Reader.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);
}
}
}
将io操作拎出来放进静态方法里就不会超时了
import java.io.IOException;
import java.io.*;
import java.util.*;
//** Class for buffered reading int and double values *//*
class Reader {
static BufferedReader reader;
static StringTokenizer tokenizer;
// ** call this method to initialize reader for InputStream *//*
static void init(InputStream input) {
reader = new BufferedReader(new InputStreamReader(input));
tokenizer = new StringTokenizer("");
}
// ** get next word *//*
static String next() throws IOException {
while (!tokenizer.hasMoreTokens()) {
// TODO add check for eof if necessary
tokenizer = new StringTokenizer(reader.readLine());
}
return tokenizer.nextToken();
}
static String nextLine() throws IOException {
return reader.readLine();
}
static int nextInt() throws IOException {
return Integer.parseInt(next());
}
static long nextLong() throws IOException {
return Long.parseLong(next());
}
static double nextDouble() throws IOException {
return Double.parseDouble(next());
}
}
public class Main {
public static void main(String[] args) throws IOException {
Reader.init(System.in);
int [][] metrix1 = get_metrix();
int [][] metrix2 = get_metrix();
if (metrix1[0].length!=metrix2.length) {
System.out.println("Error: "+metrix1[0].length+" != "+metrix2.length);
}else {
System.out.println(metrix1.length+" "+metrix2[0].length);
for (int i = 0; i < metrix1.length; i++) {
for (int j = 0; j < metrix2[0].length; j++) {
int sum = 0;
for (int k = 0; k < metrix1[0].length; k++) {
sum+=metrix1[i][k]*metrix2[k][j];
}
if (j==metrix2[0].length-1) {
System.out.println(sum);
}else {
System.out.print(sum+" ");
}
}
}
}
}
static int[][]get_metrix() throws IOException{
int r1 = Reader.nextInt();
int c1 = Reader.nextInt();
int [][] metrix1 = new int[r1][c1];
for (int i = 0; i < metrix1.length; i++) {
for (int j = 0; j < metrix1[i].length; j++) {
metrix1[i][j] = Reader.nextInt();
}
}
return metrix1;
}
}