Nature
Bumblebees solve a version of the classic 'travelling salesman' problem
Given several flowers to visit in an unfamiliar patch, bumblebees don't just fly to whichever is nearest next — after a few exploratory trips, they converge on close to the shortest possible route linking every flower, a problem that stumps even powerful computers as the number of stops grows. They appear to learn the route through trial and error, not instinct.