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  1. #include <cmath>
  2. #include <iomanip>
  3. #include <iostream>
  4. using namespace std;
  5.  
  6. struct t {
  7. 	double x, y;
  8. 	t() {
  9. 		x = 0;
  10. 		y = 0;
  11. 	}
  12. 	t(double x, double y) {
  13. 		this->x = x;
  14. 		this->y = y;
  15. 	}
  16. 	t operator+(t &tt) { return t(this->x + tt.x, this->y + tt.y); }
  17.  
  18. 	t operator-(t &tt) { return t(this->x - tt.x, this->y - tt.y); }
  19.  
  20. 	bool operator==(t &p) { return ((x == p.x) && (y == p.y)); }
  21.  
  22. 	bool operator!=(t &p) { return !(*this == p); }
  23.  
  24. 	bool t_is_line_segment(t &t1, t &t2) {
  25. 		t t3 = *this;
  26. 		t a = t2 - t1;
  27. 		t b = t3 - t1;
  28. 		double sa = a.x * b.y - b.x * a.y;
  29. 		if (sa > 0.0) return false;
  30. 		if (sa < 0.0) return false;
  31. 		if ((a.x * b.x < 0.0) || (a.y * b.y < 0.0)) return false;
  32. 		if (a.length() < b.length()) return false;
  33. 		if (t1 == t3) return false;
  34. 		if (t2 == t3) return false;
  35. 		return true;
  36. 	}
  37. 	double distance(const t &p) {
  38. 		double a = this->x - p.x;
  39. 		double b = this->y - p.y;
  40. 		return sqrt(a * a + b * b);
  41. 	}
  42.  
  43. 	double length(void) { return sqrt(x * x + y * y); }
  44. };
  45.  
  46. struct line {
  47. 	double a, b, c;
  48. 	line(const t &t1, const t &t2) {
  49. 	a = t1.y - t2.y;
  50. 	b = t2.x - t1.x;
  51. 	c = t1.x * t2.y - t2.x * t1.y;
  52. 	}
  53. };
  54.  
  55. bool intersect(const line &l1, const line &l2, t &res) {
  56. 	if (l1.a * l2.b == l2.a * l1.b)
  57. 	return false;
  58. 	double g = l1.a * l2.b - l2.a * l1.b;
  59. 	res.x = -(l1.c * l2.b - l2.c * l1.b) / g;
  60. 	res.y = -(l1.a * l2.c - l2.a * l1.c) / g;
  61. 	return true;
  62. }
  63.  
  64. int main() {
  65.  
  66. 	t x0, x1, x2, x3, m; // m точка пересечения
  67.  
  68. 	double h = 6, answer = 0;
  69.  
  70. 	cin >> x0.x >> x0.y >> x1.x >> x1.y >> x2.x >> x2.y >> x3.x >> x3.y >> h;
  71. 	double x0x1_d = x0.distance(x1);
  72. 	if (((x3.y - x2.y) * (x0.x - x1.x) - (x3.x - x2.x) * (x0.y - x1.y)) == 0) {
  73. 		if (x0.t_is_line_segment(x2, x3)) {
  74. 			if (x1.t_is_line_segment(x2, x3)) {
  75. 				if (x0x1_d <= h) {
  76. 					answer = M_PI * x0x1_d/2;
  77. 				} else {
  78. 					answer = x0x1_d * asin(h / x0x1_d);
  79. 				}
  80. 			} else {
  81. 				if (x2.t_is_line_segment(x1, x3)) {	
  82. 					if (x0x1_d <= h) answer = x0x1_d * asin(x0.distance(x2) / x0x1_d);
  83. 					else if (x0x1_d * x0x1_d <= h * h + x0.distance(x2) * x0.distance(x2)){
  84. 						answer = x0x1_d * (asin (h / x0x1_d) - acos(x0.distance(x2) / x0x1_d));
  85. 					}
  86. 				} else {
  87. 					if (x0x1_d <= h) answer = x0x1_d * asin(x0.distance(x3) / x0x1_d);
  88. 					else if (x0x1_d * x0x1_d <= h * h + x0.distance(x3) * x0.distance(x3)){
  89. 						answer = x0x1_d * (asin (h / x0x1_d) - acos(x0.distance(x3) / x0x1_d));
  90. 					}
  91. 				}
  92.  
  93. 			}
  94. 		} else {
  95. 			double a;
  96. 			if (x1.t_is_line_segment(x2, x3)) {
  97. 				a = min(x0.distance(x2), x0.distance(x3));
  98. 				if (x0x1_d < sqrt(a * a + h * h)) {
  99. 					answer = x0x1_d * acos(a / x0x1_d);
  100. 				} else {
  101. 					answer = x0x1_d * asin(a / x0x1_d);
  102. 				}
  103. 			} else {
  104. 				a = max(x0.distance(x2), x0.distance(x3));
  105. 				if (x0x1_d < sqrt(a * a + h * h)) {
  106. 					answer = x0x1_d * (asin(h / x0x1_d) - acos(a / x0x1_d));
  107. 				}
  108. 			}
  109. 		}
  110. 	} else {
  111. 		line l10(x0, x1), l23(x2, x3);
  112. 		if (intersect(l10, l23, m)) {
  113. 			if (m.t_is_line_segment(x2, x3)) {
  114. 				double x0m_d = m.distance(x0);
  115. 				answer = sqrt(x0x1_d * x0x1_d - x0m_d * x0m_d);
  116. 				if (answer > h) answer = h;
  117. 			}
  118. 		}
  119. 	}
  120. 	cout << fixed << setprecision(3) << answer << endl;
  121. 	return 0;
  122. }
Success #stdin #stdout 0s 4532KB
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https://ideone.com/jnjO1h
RFhnbyf
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
secret

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