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  1. #include <iostream>
  2. #include <vector>
  3. #include <cstdlib>
  4. #include <algorithm>
  5. #include <map>
  6.  
  7. using namespace std;
  8.  
  9. struct POINTS
  10. {
  11.    float xStart;
  12.    float yStart;
  13.    float zStart;
  14.  
  15.    float xEnd;
  16.    float yEnd;
  17.    float zEnd;
  18. };
  19.  
  20. vector<POINTS> generate_lines(int n)
  21. {
  22.     vector<POINTS> lines;
  23.  
  24.     for (int i = 0; i < n; i++)
  25.     {
  26.         POINTS p;
  27.  
  28.         p.xStart = i ? lines.rbegin()->xEnd : rand()/static_cast<float>(RAND_MAX);
  29.         p.yStart = i ? lines.rbegin()->yEnd : rand()/static_cast<float>(RAND_MAX);
  30.         p.zStart = i ? lines.rbegin()->zEnd : rand()/static_cast<float>(RAND_MAX);
  31.  
  32.         p.xEnd = i == n-1 ? lines.begin()->xStart : rand()/static_cast<float>(RAND_MAX);
  33.         p.yEnd = i == n-1 ? lines.begin()->yStart : rand()/static_cast<float>(RAND_MAX);
  34.         p.zEnd = i == n-1 ? lines.begin()->zStart : rand()/static_cast<float>(RAND_MAX);
  35.  
  36.         lines.push_back(p);
  37.     }
  38.  
  39.     random_shuffle(lines.begin(), lines.end());
  40.  
  41.     for (auto &p : lines)
  42.         if (rand()%2)
  43.         {
  44.             swap(p.xStart, p.xEnd);
  45.             swap(p.yStart, p.yEnd);
  46.             swap(p.zStart, p.zEnd);
  47.         }
  48.  
  49.     return lines;
  50. }
  51.  
  52. int main()
  53. {
  54.     vector<POINTS> lines = generate_lines(10);
  55.     multimap<tuple<double, double, double>, pair<double, double> > M;
  56.  
  57.     for (int i = 0; i < lines.size(); i++)
  58.     {
  59.         // add start point
  60.         M.insert(make_pair(make_tuple(lines[i].xStart, lines[i].yStart, lines[i].zStart),
  61.                            make_pair(i, 0) ) );
  62.  
  63.         M.insert(make_pair(make_tuple(lines[i].xEnd, lines[i].yEnd, lines[i].zEnd),
  64.                            make_pair(i, 1) ) );
  65.     }
  66.  
  67.     auto coords1 = M.begin()->first;
  68.     auto pos1 = M.begin()->second;
  69.  
  70.     vector<bool> used(lines.size(), false);
  71.  
  72.     for (int i = 0; i < lines.size(); i++)
  73.     {
  74.         std::tuple<double, double, double> coords2 = pos1.second ? make_tuple(lines[pos1.first].xStart, lines[pos1.first].yStart, lines[pos1.first].zStart) :
  75.                                                                    make_tuple(lines[pos1.first].xEnd, lines[pos1.first].yEnd, lines[pos1.first].zEnd);
  76.  
  77.         cout << pos1.first << ": " << get<0>(coords1) << " " << get<1>(coords1) << " " << get<2>(coords1) << " - "
  78.                                    << get<0>(coords2) << " " << get<1>(coords2) << " " << get<2>(coords2) << endl;
  79.  
  80.         used[pos1.first] = true;
  81.  
  82.         pair<int, int> nextPos(-1, -1);
  83.  
  84.         auto r = M.equal_range(coords2);
  85.         for (auto it = r.first; it != r.second; it++)
  86.             if (!used[it->second.first])
  87.             {
  88.                 nextPos = it->second;
  89.                 break;
  90.             }
  91.  
  92.         if (nextPos.first == -1 && i != lines.size()-1)
  93.         {
  94.             cout << "something bad happens\n";
  95.             return 1;
  96.         }
  97.  
  98.         pos1 = nextPos;
  99.         coords1 = coords2;
  100.     }
  101.  
  102.     return 0;
  103. }
  104.  
Success #stdin #stdout 0s 3472KB
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stdin
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Standard input is empty
stdout
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1: 0.108809 0.998924 0.218257 - 0.840188 0.394383 0.783099
4: 0.840188 0.394383 0.783099 - 0.79844 0.911647 0.197551
8: 0.79844 0.911647 0.197551 - 0.335223 0.76823 0.277775
0: 0.335223 0.76823 0.277775 - 0.55397 0.477397 0.628871
6: 0.55397 0.477397 0.628871 - 0.364784 0.513401 0.95223
3: 0.364784 0.513401 0.95223 - 0.916195 0.635712 0.717297
5: 0.916195 0.635712 0.717297 - 0.141603 0.606969 0.0163006
2: 0.141603 0.606969 0.0163006 - 0.242887 0.137232 0.804177
9: 0.242887 0.137232 0.804177 - 0.156679 0.400944 0.12979
7: 0.156679 0.400944 0.12979 - 0.108809 0.998924 0.218257
https://ideone.com/TuzjMn
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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