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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. #define max_n 1e-9
  5.  
  6. int t = 1, test = 1, n;
  7. struct magnet{
  8. 	double pos;
  9. 	double weight;
  10. };
  11. magnet a[12];
  12.  
  13. inline double abs_sub(double x, double y){
  14. 	return x > y ? x - y : y - x;
  15. }
  16.  
  17. int calculate(double pos_mid, int id){
  18. 	double total_l = 0, total_r = 0;
  19.  
  20. 	for(int i = id; i >= 1; i--){
  21. 		double d1 = abs_sub(pos_mid, a[i].pos);
  22. 		double wei_1 = a[i].weight;
  23. 		total_l += wei_1 / (d1 * d1);
  24. 	}
  25. 	for(int i = id + 1; i <= n; i++){
  26. 		double d2 = abs_sub(pos_mid, a[i].pos);
  27. 		double wei_2 = a[i].weight;
  28. 		total_r += wei_2 / (d2 * d2);
  29. 	}
  30.  
  31. 	double tmp = abs_sub(total_l, total_r);
  32. 	if(tmp < max_n){
  33. 		return 0;
  34. 	}
  35. 	return total_l < total_r ? 1 : 2;
  36. }
  37.  
  38. double solution(int index){
  39. 	double start = a[index].pos;
  40. 	double end = a[index+1].pos;
  41. 	double result, mid;
  42.  
  43. 	while(start <= end){
  44. 		mid = (start + end) / 2;
  45. 		if(calculate(mid, index) == 0){
  46. 			result = mid;
  47. 			break;
  48. 		}else if(calculate(mid, index) == 1){
  49. 			start = mid;
  50. 		}else{
  51. 			end = mid;
  52. 		}
  53. 		//cout << mid << endl;
  54. 	}
  55. 	return result;
  56. }
  57.  
  58. int main(){	
  59. 	freopen("input.txt", "r", stdin);
  60. 	while(t--){
  61. 		cin >> n;
  62. 		for(int i = 1; i <= n; i++){
  63. 			cin >> a[i].pos;
  64. 		}
  65. 		for(int i = 1; i <= n; i++){
  66. 			cin >> a[i].weight;
  67. 		}
  68. 		cout << "Case #" << test << endl;
  69. 		for(int i = 1; i < n; i++){
  70. 			cout << fixed;
  71. 			cout.precision(10);
  72. 			cout << solution(i) << " ";
  73. 		}
  74. 		cout << endl;
  75. 		/*for(int i = 1; i <= n; i++){
  76. 			cout << a[i].pos << " ";
  77. 		}
  78. 		for(int i = 1; i <= n; i++){
  79. 			cout << a[i].weight << " ";
  80. 		}
  81. 		cout << endl;*/
  82. 		test++;
  83. 	}
  84. 	//while(1);
  85. 	return 0;
  86. }
Success #stdin #stdout 0.01s 5280KB
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Case #1
https://ideone.com/x02CDf
language:
C++ (gcc 8.3)
created:
34 days ago
visibility:
public

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