Class participation: design a puzzle

The character need to pass the bridge which is inside the lava river. The bridge is made up of 35 blocks, half of them will be at the surface of lava but the other half will be under the lava. The condition of the blocks will exchange every ten seconds, at that time the character need to jump to a neighboring block which is floating to the top of lava. Character need to find a path to  the other side of river and also collect the inventory.