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  1. /*********************************************************//**
  2.  * Author:		migf1
  3.  * from Book:		C Programming, A Modern Approach (2nd edition)
  4.  * Chapter: 		8 (Arrays)
  5.  * Programming project: 9 (page 179) - Better implementation
  6.  ************************************************************/
  7.  
  8. #include <stdio.h>
  9. #include <stdlib.h>
  10. #include <string.h>
  11. #include <time.h>
  12.  
  13. #define NROWS			10				/* table height in rows */
  14. #define NCOLS			10				/* table width in cols  */
  15. #define NDIRS			4				/* # next-mv directions */
  16. //enum Dir { UP=0, DN, LF, RT, NDIRS };				/* allowed mv directions*/
  17.  
  18. #define EMPTY			'.'				/* empty cells' content */
  19. #define USED			"ABCDEFGHIJKLMNOPQRSTUVWXYZ"	/* used cells' contents */
  20. #define ISEMPTY(pos, tab)	( EMPTY == (tab)[ (pos) ] )	/* is tab[pos] empty?   */
  21.  
  22. #define ROW(pos)		( (pos) / NCOLS )		/* calc row-index of pos*/
  23. #define COL(pos)		( (pos) % NCOLS )		/* calc col-index of pos*/
  24.  
  25. #define POSUP(pos)		( (pos) - NCOLS )		/* calc pos minus 1 row */
  26. #define POSDN(pos)		( (pos) + NCOLS )		/* calc pos plus 1 row  */
  27. #define POSLF(pos)		( (pos) - 1 )			/* calc pos minus 1 col */
  28. #define POSRT(pos)		( (pos) + 1 )			/* calc pos plus 1 col  */
  29.  
  30. #define myMIN(x,y)		( (x) < (y) ? (x) : (y) )
  31.  
  32. /*********************************************************//**
  33.  * Store into avail[] all those positions adjacent to pos which are available to
  34.  * be selected for the next move. 
  35.  * Return the count of the available posistions found.
  36.  ************************************************************/
  37. int avail_count( const int pos, const char tab[], int avail[ NDIRS ] )
  38. {
  39. 	int temp   = 0;
  40. 	int navail = 0;
  41.  
  42. 	/* is row-up'ed pos available? */
  43. 	if ( ROW(pos) > 0 && ISEMPTY( (temp=POSUP(pos)), tab ) )
  44. 		avail[ navail++ ] = temp;
  45.  
  46. 	/* is row-dn'ed pos available? */
  47. 	if ( ROW(pos) < NROWS-1 && ISEMPTY( (temp=POSDN(pos)), tab ) )
  48. 		avail[ navail++ ] = temp;
  49.  
  50. 	/* is col-lf'ed pos available? */
  51. 	if ( COL(pos) > 0 && ISEMPTY( (temp=POSLF(pos)), tab ) )
  52. 		avail[ navail++ ] = temp;
  53.  
  54. 	/* is col-rt'ed pos available? */
  55. 	if ( COL(pos) < NCOLS-1 && ISEMPTY( (temp=POSRT(pos)), tab ) )
  56. 		avail[ navail++ ] = temp;
  57.  
  58. 	return navail;
  59. }
  60.  
  61. /*********************************************************//**
  62.  * Print the contents of the board.
  63.  ************************************************************/
  64. void tab_print( const char tab[] )
  65. {
  66. 	for (int i=0; i < NROWS * NCOLS; i++)
  67. 	{
  68. 		if ( i != 0 && i % NCOLS == 0 )
  69. 			putchar('\n');
  70. 		printf( "%c ", tab[i] );
  71. 	}
  72.  
  73. 	putchar('\n');
  74. }
  75.  
  76. /*********************************************************//**
  77.  *
  78.  ************************************************************/
  79. int main( void )
  80. {
  81. 							/* total # of moves allowed     */
  82. 	const int 	NMOVES = myMIN( NROWS*NCOLS, (int)(strlen(USED) - 1) );
  83. 	int 		pos = 0, imove = 0;		/* current pos & moves counter  */
  84. 	char 		tab[ NROWS * NCOLS ];		/* our un-initialized board     */
  85. 	int		avail[ NDIRS ] = {-1,-1,-1,-1}; /* available neighbor positions */
  86.  
  87. 	srand( (unsigned)time(NULL) );			/* init pseudo-random seed      */
  88. 	memset( tab, EMPTY, sizeof(tab) );		/* init table with dots         */
  89.  
  90. 	tab[0] 	= USED[0];				/* start with filled 1st pos    */
  91. 	while ( imove < NMOVES )
  92. 	{
  93. 		int navail = avail_count(pos, tab, avail);
  94. 		if ( 0 == navail )
  95. 			break;
  96. 		pos = avail[ rand() % navail ];
  97. 		tab[ pos ] = USED[ ++imove ];
  98. 	}
  99. 	tab_print( tab );
  100.  
  101. 	exit( EXIT_SUCCESS );
  102. }
  103.  
Success #stdin #stdout 0.01s 1720KB
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F E D . . . . . . . 
G . K L . . . . . . 
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https://ideone.com/fT57L
language:
C99 (gcc 8.3)
created:
13 years ago
visibility:
public

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