12. The system of claim 10 , wherein the processor is configured to determine the searching cost associated with the navigation hierarchical structure diagram includes the processor is configured to: calculate a viewing cost of the navigation hierarchical structure diagram based at least in part on confidence levels of leaf nodes associated with the navigation hierarchical structure diagram and branch positions corresponding to the leaf nodes; calculate a clicking cost of the navigation hierarchical structure diagram based at least in part on confidence levels of the leaf nodes and hierarchical positions corresponding to the leaf nodes; and calculate the searching cost associated with the navigation hierarchical structure diagram based at least in part on the clicking cost and the viewing cost.
12. The system of claim 10 , wherein the processor is configured to determine the searching cost associated with the navigation hierarchical structure diagram includes the processor is configured to: calculate a viewing cost of the navigation hierarchical structure diagram based at least in part on confidence levels of leaf nodes associated with the navigation hierarchical structure diagram and branch positions corresponding to the leaf nodes; calculate a clicking cost of the navigation hierarchical structure diagram based at least in part on confidence levels of the leaf nodes and hierarchical positions corresponding to the leaf nodes; and calculate the searching cost associated with the navigation hierarchical structure diagram based at least in part on the clicking cost and the viewing cost. 16. The system of claim 12 , wherein the processor is configured to calculate the clicking cost of the navigation hierarchical structure diagram based at least in part on confidence levels of the leaf nodes and hierarchical positions corresponding to the leaf nodes includes the processor is configured to: add products of corresponding confidence levels and hierarchical positions in the navigation hierarchical structure diagram for all leaf nodes of the navigation hierarchical structure diagram.