[Java] 蓝桥杯BASIC-17 基础练习矩阵乘法

问题描述
给定一个N阶矩阵A，输出A的M次幂（M是非负整数）
例如：
A =
1 2
3 4
A的2次幂
7 10
15 22
输入格式
第一行是一个正整数N、M（1<=N<=30, 0<=M<=5），表示矩阵A的阶数和要求的幂数
接下来N行，每行N个绝对值不超过10的非负整数，描述矩阵A的值
输出格式
输出共N行，每行N个整数，表示A的M次幂所对应的矩阵。相邻的数之间用一个空格隔开
样例输入
2 2
1 2
3 4
样例输出
7 10
15 22

package base17;

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int m = in.nextInt();
        in.close();
        long[][] a = new long[40][40];
        long[][] b = new long[40][40];
        long[][] t = new long[40][40];
        //输入
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                a[i][j] = in.nextLong();
                t[i][j] = a[i][j];
            }
        }
        //0次幂  输出单位矩阵
        if (m == 0) {
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    if (i == j) {
                        System.out.print(1 + " ");
                    } else {
                        System.out.print(0 + " ");
                    }
                }
                System.out.println();
            }
            return;
        }
        //m次幂
        while (--m > 0) {
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    int k = n;
                    while (k > 0) {
                        b[i][j] += t[i][k - 1] * a[k - 1][j];
                        k--;
                    }
                }
            }
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    t[i][j] = b[i][j];
                    b[i][j] = 0;
                }
            }
        }


        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                System.out.print(t[i][j] + " ");
            }
            System.out.println();
        }
    }
}

package base17;

import java.util.Scanner;

public class Main {

public static void main(String[] args) {

Scanner in = new Scanner(System.in);

int n = in.nextInt();

int m = in.nextInt();

in.close();

long[][] a = new long[40][40];

long[][] b = new long[40][40];

long[][] t = new long[40][40];

//输入

for (int i = 0; i < n; i++) {

for (int j = 0; j < n; j++) {

a[i][j] = in.nextLong();

t[i][j] = a[i][j];

}

//0次幂输出单位矩阵

if (m == 0) {

for (int i = 0; i < n; i++) {

for (int j = 0; j < n; j++) {

if (i == j) {

System.out.print(1 + " ");

} else {

System.out.print(0 + " ");

}

System.out.println();

}

return;

}

//m次幂

while (--m > 0) {

for (int i = 0; i < n; i++) {

for (int j = 0; j < n; j++) {

int k = n;

while (k > 0) {

b[i][j] += t[i][k - 1] * a[k - 1][j];

k--;

}

for (int i = 0; i < n; i++) {

for (int j = 0; j < n; j++) {

t[i][j] = b[i][j];

b[i][j] = 0;

}

for (int i = 0; i < n; i++) {

for (int j = 0; j < n; j++) {

System.out.print(t[i][j] + " ");

}

System.out.println();

}

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