Implement max pooling test

include/layers/max_pooling.cuh

@@ -3,8 +3,8 @@
 
 #include <cuda_runtime.h>
 
-#include "layer.cuh"
 #include "activation.cuh"
+#include "layer.cuh"
 
 namespace CUDANet::Layers {
 
@@ -21,6 +21,15 @@ class MaxPooling2D : public SequentialLayer {
 
     float* forward(const float* d_input);
 
+    /**
+     * @brief Get the output width (/ height) of the layer
+     *
+     * @return int
+     */
+    int getOutputSize() {
+        return outputSize;
+    }
+
   private:
     int inputSize;
     int nChannels;