| 摘要 |
Navigation devices, methods, and programs store map data hierarchically with the map data of a hierarchy level being excluded. The devices, methods, and programs read the stored map data, perform a route search within each predetermined area on a departure point side and a destination side, and acquire a shortest cost route in a range overlapped in search areas. In a hierarchy level having a proximal higher hierarchy level of which the map data does not exist, the devices, methods, and programs expand the predetermined area into a search area in the proximal higher hierarchy level and acquire a first shortest cost route, and perform the route search in a higher hierarchy level to acquire a second shortest cost route. When the second shortest cost route's cost is smaller than the first shortest cost route's cost, the devices, methods, and programs update the cost of the shortest cost route.
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