Greedy

A greedy algorithm makes the locally best choice at every step and never looks back; it is correct only when you can prove that some optimal answer agrees with that choice.

To fit the most non-overlapping activities, sort by end time and keep every activity that starts after the last one you kept ends.

Track the farthest index you can reach so far; if you ever stand beyond it you are stuck, and counting how often you must extend that frontier gives the minimum number of jumps.

If total gas covers total cost a valid start exists, and it is the station right after the last point where the running tank went negative.

When combining two items costs their total size and you must combine everything, always merge the two smallest first, using a min-heap.