Fig. 2. Schematic for the exploitation of computing resources of blockchain nodes in different consensus algorithms.

Each small square represents the computational resource of a node, and the color on it indicates whether its resource is utilized and whether a valid result is obtained. The occurrence of multiple colors on a square indicates the presence of multiple situations. N denotes that the node gets a solution that does not pass local validation. Yh means that the node gets the solution to the issued meaningless problem. Yo indicates that the node gets the solution to the issued meaningful problem. IA means that the node is not activated to solve the issued problem. The interval (0, 1) represents that the node gets a feasible solution to the meaningful optimization problem, and the magnitude of this value represents the optimality of the solution, where 0 and 1 indicate the node with no feasible and an optimal solution, respectively.