Determine the spring constant of the spring

Question

A small 0.10 kg block starts from rest at point A, which is at a height of 1.0 m. The surface between points A and B and between points C and D is frictionless, but is rough between points B and C, having a coefficient of friction of 0.10. After traveling the distance â„“ = 1.0 m, the small block strikes a larger block of mass 0.30 kg, and sticks to it, compressing the spring to a maximum distance x = 0.50 m. Determine the spring constant of the spring.