Source code for submission s1216

ants.cpp

  1.  
  2. #include <stdio.h>
  3. #include <list>
  4. #include <iostream>
  5.  
  6. class Ant
  7. {
  8.  public:
  9.   int facing;
  10.   int pos;
  11.   Ant(int fac, int p) : facing(fac), pos(p) {}
  12. };
  13.  
  14. #define FACE_R 0
  15. #define FACE_L 1
  16.  
  17. bool swapped;
  18.  
  19. void swap(int & a, int & b)
  20. {
  21. 	int temp = a;
  22. 	a = b;
  23. 	b = temp;
  24. 	swapped = true;
  25. }
  26.  
  27. using namespace std;
  28.  
  29. bool compare(const Ant & a, const Ant & b)
  30. {
  31. 	if (a.pos < b.pos)
  32. 		return 1;
  33. 	return 0;
  34. }
  35.  
  36. int main()
  37. {
  38. 	int ants_num, lumber_size;
  39. 	int ant1, ant2 = -1;
  40. 	int max_length = 0;
  41. 	int number_facings = 0;
  42. 	list<Ant> ants_array;
  43. 	while(scanf("%d%d", &lumber_size, &ants_num) == 2)
  44. 	{
  45. 		ants_array.clear();
  46. 		max_length = 0;
  47. 		number_facings = 0;
  48. 		ant2 = -1;
  49. 		for (int i = 0; i < ants_num; i++)
  50. 		{
  51. 			int pos;
  52. 			char facing;
  53. 			scanf("%d %c", &pos, &facing);
  54. 			ants_array.insert(ants_array.end(), Ant(facing == 'R' ? FACE_R : FACE_L, pos));
  55. 			int distance = facing == 'R' ? lumber_size - pos : pos;
  56. 			if (distance > max_length)
  57. 				max_length = distance;
  58. 			if (facing == 'L')
  59. 				number_facings++;
  60. 		}
  61. 		ants_array.sort(compare);
  62.  
  63. 		list<Ant>::iterator itr = ants_array.begin();
  64. 		for (int i = 0; i < number_facings; i++)
  65. 		{
  66. 			itr++;
  67. 		}
  68. 		list<Ant>::iterator first = ants_array.begin();
  69. 		list<Ant>::iterator last = --ants_array.end();
  70. 		int num2 = itr->pos;
  71. 		itr--;
  72. 		int num1 = itr->pos;
  73.  
  74. 		ant1 = 0;
  75.  
  76. 		while (first->facing == FACE_L && first != ants_array.end())
  77. 			first++;
  78. 		while (last->facing == FACE_R && last != ants_array.begin())
  79. 			last--;
  80. 		if (first != ants_array.end() && first->pos > lumber_size - last->pos)
  81. 		{
  82. 			ant1 = num1;
  83. 		}
  84.  
  85. 		if (first != last && first->pos < lumber_size - last->pos)
  86. 		{
  87. 			ant1 = num2;
  88. 		}
  89.  
  90. 		if (first != last && first != ants_array.end() && first->pos == lumber_size - last->pos)
  91. 		{
  92. 			ant1 = num1;
  93. 			ant2 = num2;
  94. 		}
  95. 		/*
  96. 		if (itr == ants_array.end())
  97. 		{
  98. 		  ant1 = (--itr)->pos;
  99. 		}
  100. 		else
  101. 		if (itr == ants_array.begin())
  102. 		{
  103. 		  ant1 = itr->pos;
  104. 		}
  105. 		else
  106. 		{
  107. 			int pos1 = lumber_size - itr->pos;
  108. 			int num1 = itr->pos;
  109. 			int pos2 = (--itr)->pos;
  110. 			int num2 = itr->pos;
  111. 			cout << num1 << " "<< num2 << endl;
  112. 			if (pos1 > pos2)
  113. 				ant1 = num1;
  114. 			else if (pos1 < pos2)
  115. 				ant1 = num2;
  116. 			else
  117. 			{
  118. 				ant1 = num1;
  119. 				ant2 = num2;
  120. 			}
  121. 		}*/
  122. 		printf("The last ant will fall down in %d seconds - started at %d",max_length, ant1);
  123. 		if ( ant2 != -1)
  124. 			printf(" and %d",ant2);
  125.  
  126. 		printf(".\n");
  127. 	}
  128.  
  129. }
  130.