Question 10
David cycles to the park (Công viên) along the pictured route. Circular endpoints divide it into dotted or striped road segments. At each battery icon he may replace the battery, resetting its charge to exactly 20%.
The mode table is preserved below (chậm=slow, nhanh=fast, giây=seconds). For a dotted segment, slow takes 20 s and 5% charge, fast 10 s and 10%. For a striped segment, slow takes 40 s and 10%, fast 20 s and 20%. A mode can change only between segments.
Starting with 20% charge, David must not run out of charge while moving. What is the shortest travel time?
Editorial endpoint convention: a battery may reach 0% exactly on arrival at a replacement station, where it is replaced before further travel; replacement time is not specified and is treated as zero.
The mode table is preserved below (chậm=slow, nhanh=fast, giây=seconds). For a dotted segment, slow takes 20 s and 5% charge, fast 10 s and 10%. For a striped segment, slow takes 40 s and 10%, fast 20 s and 20%. A mode can change only between segments.
Starting with 20% charge, David must not run out of charge while moving. What is the shortest travel time?
Editorial endpoint convention: a battery may reach 0% exactly on arrival at a replacement station, where it is replaced before further travel; replacement time is not specified and is treated as zero.