基础练习 矩阵乘法

//#define LOCAL
#include <cstdio>
#include <cstring>
#define MAX_X 30
#define MAX_Y 30

int n, m;
struct Matrix
{
	int x, y;  //角标
	int a[MAX_X][MAX_Y]; //内容 
	void clear()
	{
		x = y = 0;
		memset(a, 0, sizeof(a));
	}
};

void PrintMatrix(Matrix &a, int n)
{
	for(int i = 0; i < n; i++)
	{	
		int first = 1;
		for(int j = 0; j < n; j++)
		{
			if(first)
			{
				printf("%d", a.a[i][j]);
				first = 0;
			}
			else
			{
				printf(" %d", a.a[i][j]);
			}
		}
		printf("\n");
	}
}

Matrix Multiplication(Matrix &a, Matrix &b)   //n:阶数  ， count：幂 -1
{
	Matrix tmp;
	tmp.clear();   //初始化矩阵 
	for(int k = 0; k < n; ++k)  //k:积矩阵行
	{
		for(int x = 0; x < n; ++x) 
		{
			for(int y = 0; y < n; ++y)
			{
				tmp.a[k][x] += a.a[k][y] * b.a[y][x];
			}
		}
	} 

	return tmp;
}

int main()
{
#ifdef LOCAL
	freopen("input3.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
	Matrix a, ans;
	scanf("%d", &n);
	scanf("%d", &m);
	a.x = a.y = n; 
	for(int i = 0; i < a.x; i++)
	{
		for(int j = 0; j < a.y; j++)
		{
			scanf("%d", &a.a[i][j]);
			ans.a[i][j] = a.a[i][j];
		}
	}
	if(m == 0)
	{
		for(int i = 0; i < n; i++)
		{
			for(int j = 0; j < n; j++)
			{
				ans.a[i][j] = (i == j) ? 1 : 0;	
			}	
		}	
	} 
	else
	{
		for(int i = 0; i < m-1; i++)
		{
			ans = Multiplication(ans, a);
		}
	}
	PrintMatrix(ans, n);
	return 0;
}

struct Matrix
{
	int n, m;
	int a[MAXN][MAXM];
	void clear()
	{
		n = m = 0;
		memset(a, 0, sizeof(a));
	}
	Matrix operator * (const Matrix &b) const
	{
		Matrix tmp;
		tmp.clear();
		tmp.n = n;
		tmp.m = b.m;
		for(int i = 0; i < n; ++i)
		{
			for(int j = 0; j< b.m; ++j)
			{
				for(int k = 0; k < m; ++k)
				{
					tmp.a[i][j] += a[i][k] * b.a[k][j];
				}
			}
		}
		return tmp;
	}
};