回环矩阵

#include <stdio.h>

int main()
{
	int n ;
	int a[20][20] ;

	printf("输入n的值:") ;
	scanf("%d" , &n ) ;

	// 初始化
	int j = 0 ;
	int i = 0 ;
	int k = 0 ;
	int m = 0 ; 
	int p = 0 ;
	int number = 0 ;

	for( i = 0 ; i < n*n  ; i++ )
	{  
		for( k = i ; k <= n - i - 2 ; k++ )
		{
			number++ ;
			a[i][k] = number ;
		}

		for( m = i ; m <= n - i - 2 ; m++ )
		{
			number++ ;
			a[m][n-i-1] = number ; 
		}

		for( j = n - i - 1  ; j >= i + 1 ; j-- )
		{
			number++ ;
			a[n-i-1][j] = number ;
		}

		for( p = n - i - 1 ; p >= i + 1 ; p-- )
		{
			number++ ;
			a[p][i] = number ;
		}

		if( n*n  == number + 1 )
		{
			a[n/2][n/2] = number + 1 ;
			break ;
		}
	}

	// 按格式输出
	for( i = 0 ; i < n ; i++ )
	{
		for( j = 0 ; j < n ; j++ )
		{
			printf( "%d " , a[i][j] ) ;
		}
		printf("\n") ;
	}
	return 0 ;
}