蓝桥杯 BASIC 27 矩阵乘法（矩阵、二维数组）

【思路】：注意0次幂是单位矩阵。

【AC代码】：

#include <iostream>
#include <algorithm>
#include <iomanip>
#include <cstdio>
#include <cstring>
using namespace std;

#define MAX 30+2

void cal(int m[MAX][MAX], int t[MAX][MAX], int r[MAX][MAX], int N)
{
	int i = 0, j = 0, k = 0;
	for (i = 0; i < N; i++)
	{
		for (j = 0; j < N; j++)
		{
			int temp = 0;
			for (k = 0; k < N; k++)
			{
				temp += m[i][k] * t[k][j];
			}
			r[i][j] = temp;
		}
	}
}

void copy(int t[MAX][MAX], int r[MAX][MAX], int N)
{
	int i = 0, j = 0;
	for (i = 0; i < N; i++)
	{
		for (j = 0; j < N; j++)
		{
			t[i][j] = r[i][j];
		}
	} 
}

int main()
{
	//freopen("in.txt", "r", stdin);
	//freopen("out.txt", "w", stdout);
	int N = 0, M = 0, matrix[MAX][MAX], temp[MAX][MAX], res[MAX][MAX];
	int i = 0, j = 0;
	
	//input
	cin >> N >> M;
	for (i = 0; i < N; i++)
	{
		for (j = 0; j < N; j++)
		{
			cin >> matrix[i][j];
			if (i == j)
			{
				temp[i][j] = 1;
				res[i][j] = 1;
			}
			else
			{
				temp[i][j] = 0;
				res[i][j] = 0;
			}
		}
	}
	
	//cal
	for (i = 0; i < M; i++)
	{
		cal(matrix, temp, res, N);
		copy(temp, res, N);
	}
	
	for (i = 0; i < N; i++)
	{
		for (j = 0; j < N; j++)
		{
			cout << res[i][j] << " ";
		}
		cout << endl;
	}
	return 0;
}