【C++ 】STL求全排列和组合

排列组合 c++实现

// id 0-14 or 1-15 all nums chosed 5 groups
 std::vector<uint8_t> candidates = {14,13,12,11,10,9,8,7,6,5,4,3,2,1,0};
 std::vector<std::vector<uint8_t>> combines = Combine(candidates,5);


std::vector<std::vector<uint8_t>> GeoHash::Combine(std::vector<uint8_t> &combines,int size)
{
  std::vector<std::vector<uint8_t>> ret;
  if (combines.size() == size){
    ret.push_back(combines);
    return ret;
  }
  //out judge
  if (1 == size){
    for (auto &item : combines)
    {
      std::vector<uint8_t> vtTemp;
      vtTemp.push_back(item);
      ret.push_back(vtTemp);
    }
    return ret;
  }
  int i = 1;
  for (auto it = combines.begin(); it != combines.end() && (combines.size() - i) >= (size - 1);it++, i++)
  {
    if (it + 1 != combines.end())
    {
      std::vector<uint8_t> vtBack(it + 1, combines.end());
      std::vector<std::vector<uint8_t>> vtCombi1 = GeoHash::Combine(vtBack, size - 1);
      for (auto &item : vtCombi1)
      {
        item.push_back(*it);
      }
      ret.insert(ret.end(), vtCombi1.begin(), vtCombi1.end());
    }
  }
  return ret;
}
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https://blog.csdn.net/tomwillow/article/details/81133932