text: #include "caffe2/operators/minmax_ops.h"
  
  #include <string>
  #include <vector>
  
  #include "caffe2/utils/eigen_utils.h"
  
  namespace caffe2 {
  
  template <typename T, class Context>
  bool SelectGradientOpBase<T, Context>::RunOnDevice() {
    const auto& Y = Input(0);
    const auto& dY = Input(1);
    const int N = Y.numel();
    ConstEigenVectorArrayMap<T> Y_arr(Y.template data<T>(), N);
    ConstEigenVectorArrayMap<T> dY_arr(dY.template data<T>(), N);
    for (int i = 0; i < OutputSize(); i++) {
      const auto& Xi = Input(i + 2);
      auto* dXi = Output(i, Xi.sizes(), at::dtype<T>());
      ConstEigenVectorArrayMap<T> Xi_arr(Xi.template data<T>(), N);
      EigenVectorArrayMap<T> dXi_arr(dXi->template mutable_data<T>(), N);
      dXi_arr = (Xi_arr == Y_arr).template cast<T>() * dY_arr;
    }
    return true;
  }
  
  REGISTER_CPU_OPERATOR(MaxGradient, MaxGradientOp<float, CPUContext>);
  REGISTER_CPU_OPERATOR(MinGradient, MinGradientOp<float, CPUContext>);
  
  OPERATOR_SCHEMA(MaxGradient).NumInputs(3, INT_MAX).NumOutputs(1, INT_MAX);
  OPERATOR_SCHEMA(MinGradient).NumInputs(3, INT_MAX).NumOutputs(1, INT_MAX);
  
  namespace {
  
  class GetMaxGradient : public GradientMakerBase {
    using GradientMakerBase::GradientMakerBase;
    std::vector<OperatorDef> GetGradientDefs() override {
      std::vector<std::string> inputs = {O(0), GO(0)};
      std::vector<std::string> grad_inputs;
      for (int i = 0; i < def_.input_size(); ++i) {
        inputs.push_back(I(i));
        grad_inputs.push_back(GI(i));
      }
      return SingleGradientDef("MaxGradient", "", inputs, grad_inputs);
    }
  };
  
  class GetMinGradient : public GradientMakerBase {
    using GradientMakerBase::GradientMakerBase;
    vector<OperatorDef> GetGradientDefs() override {
      std::vector<std::string> inputs = {O(0), GO(0)};
      std::vector<std::string> grad_inputs;
      for (int i = 0; i < def_.input_size(); ++i) {
        inputs.push_back(I(i));
        grad_inputs.push_back(GI(i));
      }
      return SingleGradientDef("MinGradient", "", inputs, grad_inputs);
    }
  };
  
  } // namespace
  
  REGISTER_GRADIENT(Max, GetMaxGradient);
  REGISTER_GRADIENT(Min, GetMinGradient);
  
  } // namespace caffe2
  