camillac / holmies

mazeSolver project

holmies

mazeSolver project

personnel

Camilla Cheng & Lisa Ye

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Maze Solver

Statement of problem

What is the boolean value of the statement "it is possible to make a path from explorer's current position to treasure"?

Recursive abstraction

When I'm asked
    if it is possible to find a path to the treasure,
the recursive abtraction can say
    if it is possible to find a path to the treasure from a point next to the the explorer's current location

Base case

• When explorer is on treasure, return true
• When explorer is on a wall, return false

Pseudocode of algorithm

if (explorer is on treasure)
    return true;
if (explorer is on wall)
    return false;
else {
    take a snapshot of maze; // saves image of maze before the explorer moves to a new spot
    for ( each spot in all four directions [N,E,S,W] next to the current position ) {
        drop a wall on current location;
        move explorer to the new spot (in the direction mentioned in the for loop);
        if ( [RECURSIVE ABSTRACTION: repeat the problem starting with that new spot] ) {
            return true;
        }
        else {
            set current maze to snapshot; // reset the image of the maze to before the explorer moved
        }
    }
    return false;
}

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Class(es), with fields and methods

Maze

Fields

• int[][] maze
• representation of treasure
• representation of wall
• representation of stepping stone
• rep of directions [N,E,S,W]

Methods

• public Maze
• public go(direction)
• public explorerIsOnA(location)
• public toString

UserOfMaze

Fields

• Maze m

Methods

• public static void main(String[] args)

---

Known Bugs/Issues

• nullPointer error when testing on big maze(1 rank, 3 files)
• Snapshot is being replaced on every recursive call
• Need to change parameter in for loop

Version n

• Find and return all of the solutions of the maze
• Find the shortest solution to the maze
• Build a nice visual of the maze

holmies's Issues

format pseudocode like code, not English

Your pseudocode would be easier for me to read if it used indentation, like Python. Check out Quoting code in GitHub's documentation for its version of markdown.

hw95 README issues

Solid work! The solution looks mostly correct.
As Holmes mentioned make sure to take snapshots and use them when backtracking. One nit-picky thing is that saying "for every spot next to location" is a little vague since it can be any spot, not just a single step north, east, south, or west.

"big"

Mere personal reaction: I am a giant fan of the use of "big" in your README to refer to a maze that has three (3) cells.

Also, I liked the strikethrough in the "Bugs" section

issues from spot-checks

Don't panic!

Your project has a new issue opened for it because I used your team's work to spot-check progress for the class. Having observed a potential improvement, it seemed worth passing it along directly to you, in addition to considering presenting it in class, anonymously.

meaning of "start"

statement of problem

Your use of "the start" is unclear to me, so it may be unclear to you also.

If it means something like

the explorer's location at the beginning of a particular execution of the recursive procedure

then your thinking looks good. It would help communication to make that thinking clear in the English.

On the other hand, if "the start" means something like

the root call for this problem

then your "statement of problem" fails to apply to the recursive abstraction. You will want to correct that.

You used "the start" in your recursive abstraction also (as one would expect), so make sure the meaning there is also clear, and consistent with the meaning here.

NTTSTT?

Your pseudo code is on the right track. But "if (new spot is not a WALL)" seems redundant with the base case check.

snapshot-restore

Since I'm looking at your pseudocode anyway:

I see where you drop a wall appropriately. But I'm also expecting some kind of snapshot-restore pair to get rid of that wall. It will likely take a bit of hard thinking to decideout where to put the snapshot and the restore.

Lot of people will have the challenge of that thinking, so lots of people will be helped by a Piazza post, if that sounds appropriate.

hw93 feedback

Please proofread your work. That is your job, not my job.

statement of problem

"expression" makes little sense. You probably mean "value".

recursive abstraction

"When I'm asked to if it is possible" Verb?

base cases

Please reconsider the "1 step/space". I recommend a smaller base case. As usual, smaller base cases are easier to program.

replace link in repo-of-holding

See email of Mon 2018-04-02 07:51