I promised to post the code that got this result on the trickyFood problem. 

This is the line that runs the trickyFood problem in the pacman.py file.

args = readCommand(['-l', 'trickyFood', '-p', 'AStarFoodSearchAgent', '-z', '0.65'])

Path found with total cost of 60 in 0.2 seconds
Search nodes expanded: 206
Pacman emerges victorious! Score: 570

(This code got 26/25 from the autograder.)

Four files are attached: pacman.py, problems.py (where I gathered all the problems), search.py, and searchAgents.py. (Some of the imports in other files may need adjustment since I moved some functions and classes around a bit.)

The food heuristic is generalized and is called the blobHeuristic. It's in search.py. The result above also depends on the priority function, which is associated with A*. It's in aStarSearch, also in search.py.

The corners problem and the food problem both use the blobHeuristic since they are essentially the same problem: visit a given set of grid positions.

Post questions if you have any.