Source code for submission s925

ants.c

  1. #include <stdio.h>
  2. #include <string.h>
  3. #define false 0
  4. #define true 1
  5.  
  6. char inv(char c){
  7. 	return c=='L' ? 'R' : 'L';
  8. }
  9. int main( int agrc, char * argv[] ) {
  10. 	char array[100002],c, remL, remR;
  11. 	int i, wood=10, ants, coo, remaining, pL, pR, timeL, timeR;
  12. 	int waitL, waitR;	
  13. 	int distL, distR;
  14. 	int max=-1, len;
  15. 	while( scanf("%d %d", &wood, &ants ) != EOF ) {
  16. 		waitL = false;
  17. 		waitR = false;
  18. 		pL = wood;
  19. 		pR = 0;		
  20. 		max = -1;
  21. 		memset(array, ' ', wood+1);
  22. 		for( i = 0 ; i < ants ; i++ ) {
  23.         	scanf("%d %c", &coo, &c );
  24. 			array[coo] = c;
  25. 			if(coo > pR) pR = coo;
  26. 			if(coo < pL) pL = coo;  
  27. 		}
  28. 		remaining = ants;
  29. 		remL = 'L';
  30. 		remR = 'R';
  31. 		timeL = 0;
  32. 		timeR = wood;
  33. 		len = 0;
  34. 		while(timeL < wood) {
  35. 			if(array[timeL] == 'R'){
  36. 				max = wood-len;	
  37. 				break;
  38. 			}
  39. 			timeL++;
  40. 			len++;	
  41. 		}
  42. 		len = 0;
  43. 		while(timeR >= 0) {
  44. 			if(array[timeR] == 'L'){
  45. 				if(wood-len>max) max = wood-len;
  46. 				break;
  47. 			}
  48. 			timeR--;
  49. 			len++;	
  50. 		}
  51. 		while(remaining > 2 && pL < pR) {
  52. 			if(waitL == false){
  53. 				while(array[pL] == ' ') pL++;
  54. 				if(array[pL] == remL){
  55. 					remaining--;
  56. 					array[pL] = ' ';	
  57. 					pL++;		
  58. 				} else if(array[pL] == inv(remL)) {
  59. 					remL = inv(remL);
  60. 					if(waitR == false)
  61. 						waitL = true;
  62. 					waitR = false;
  63. 				}
  64. 			}
  65. 			if(waitR == false && remaining > 2){
  66. 				while(array[pR] == ' ') pR--;
  67. 				if(array[pR] == remR){
  68. 					remaining--;
  69. 					array[pR] = ' ';
  70. 					pR--;
  71. 				} else if(array[pR] == inv(remR)){
  72. 					remR = inv(remR);
  73. 					if(waitL == false)
  74. 						waitR = true;
  75. 					waitL = false;
  76. 				}
  77. 			}
  78. 			//for( i = 0 ; i < wood ; i++ )
  79. 			//	printf("%c", array[i]);
  80. 			//printf(",  rem: %c %c,    p: %2d %2d,  wait: %d %d,  remaining: %d\n", remL, remR, pL, pR, waitL, waitR, remaining);
  81. 		}
  82. 		while(array[pL] == ' ') pL++;
  83. 		while(array[pR] == ' ') pR--;
  84.  
  85. 		distL = array[pL] == ' ' ? wood+123 : pL;
  86. 		distR = array[pL] == ' ' ? wood+123 : wood-pR;
  87. 		printf("The last ant will fall down in %d seconds - ", max);
  88. 		if(distL > distR || pL == pR){
  89. 			printf("started at %d.\n", pL);		
  90. 		}
  91. 		if(distR > distL && pL != pR){
  92. 			printf("started at %d.\n", pR);		
  93. 		}
  94. 		if(distR == distL){
  95. 			printf("started at %d and %d.\n", pL, pR);		
  96. 		}
  97. 	}	
  98.  
  99. 	return 0;
  100. }
  101.