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Two Additional Variations

As you arrive snarf the code for today’s class. Then go ahead and run Blob.java. Play around with running File->new blobs and File->count blobs. Two Additional Variations. Recursion on grids Recursion with 2 player games GridGame apt Maybe a brief visit back to stacks and queues. Blobs.

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Two Additional Variations

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  1. As you arrivesnarf the code for today’s class. Then go ahead and run Blob.java. Play around with running File->new blobs and File->count blobs.

  2. Two Additional Variations • Recursion on grids • Recursion with 2 player games • GridGame apt • Maybe a brief visit back to stacks and queues

  3. Blobs • Modify Blobs.java to use BlobModel rather than IterativeBlobModel • Go into BlobModel and finish the blobFill Function (bear in mind it must both modify the board AND return the size of the final blob)

  4. 2 Player Games • Imagine a numbers game played with 2 players who takes turns • The game starts with a particular number • Each turn, a player can subtract 1 2 or 3 from the number • The player who reduces the number to 0 (or below) wins • Consider the function willFirstPlayerWin(intstartingNum) which determines if the first player wins if both players play perfectly • How can we solve this problem recursively? • HINT: willFirstPlayerWin(5) is truebecause willFirstPlayerWin(4) is false. In more normal terms, if the game starts at 5, player1 can reduce it to 4, and then player2 can’t win from 4.

  5. 2 Player Games • Imagine a numbers game played with 2 players who takes turns • The game starts with a particular number • Each turn, a player can subtract 1 2 or 3 from the number • The player who reduces the number to 0 (or below) wins • player 1 wins if player 2 can’t win • So player 1 wants to move the number to something unwinnable • If player 1 can’t do that, player 2 will win • Example: for 4…player 1 can move it to 1 2 3 – any one of those player 2 can win from. • So… if i can win the game right now, then return true for each number I can move the game to if that number is unwinnable (recursion!) return true return false

  6. GridGame • COMBINES grid work and 2 player recursive decdent • It’s available in the APT section of the website • My starting code is in the code you snarfed • There are HINTS below, but try to work with those nearby and solve the problem without hints • Not currently assigned, but I wouldn’t be surprised if it showed up on a later APT set so be sure to keep your code • If you finish early, take a look at IterativeBlobModel and try to understand how the non recursive blobFill function works

  7. Iterative Blob Model • Look and work with those nearby to write an English language description of how it works • You’ll know you really understand it when: • You know how you would change the algorithm to make it work for diagonals (small change) • You know if the algorithm would still work if you used a stack instead of a queue

  8. Which line would you need to change to make diagonals work? • Line 1 • Line 2 • Line 3 • Line 4 • Line 5

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