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# How do I complete this code to work effectively?

Posted on 2008-10-07
Medium Priority
322 Views
All in C# language
I seeking help in extending the  implementation of the mimimax algorithm  in  this program so that
(1).  in addition to the variable that holds the minimax value of the node, the node has a

variable that holds the board position. The value of this variable can simply be an array of

length nine which takes the values x and o (or 1 and -1, if you prefer integers).

(2).    the tree is generated automatically by computing the successor states for the board

position represented by a particular node. Start with the empty board for the root node

and recursively compute the successors until you reach terminal nodes.

(3). the data value of a terminal node is determined by the board position that it represents:

1, if Max wins

0, if it is a draw

-1, if Min wins

(4). after running the program, all nodes should have the appropriate minimax values.
``````using System;
using System.Collections.Generic;

using System.Text;

public class Minimax

{

static void Main(string[] args)

{

// generate a simple game tree, starting with the root

Tree tree = new Tree(0);

// children of the root

tree.children = new Forest(new int[] { 0, 0 });

// children of the left child of the root

tree.children.first.children = new Forest(new int[] { 0, 7, 9 });

// children of the right child of the root

tree.children.rest.first.children = new Forest(new int[] { 4, 8, 6 });

// children of the leftmost child of the left child of the root

tree.children.first.children.first.children = new Forest(new int[] { 5, 3, 1 });

// write the expected and calculated minimax values to the console

Console.WriteLine("Expected minimax value is 5");

Console.WriteLine("Calculated minimax value of the tree " + tree.Minimax(true));

Console.WriteLine("Press any key to exit ...");

} // end method Main

private class Tree

{

public int data; // data stored in node

public Forest children; // link to the children of the node

// create a tree without children and initialize data

public Tree(int nodeData)

{

data = nodeData;

children = null; // node has no children

} // end constructor

// determine the minimax value of the node

public int Minimax(Boolean maximise)

{

// this method calculates the minimax value for the tree, which is:

// - the value in data, if the tree is a leaf

if (children == null) return data;

// - the maximum of the minimax values of the subtrees, if maximise is true

if (maximise) return children.Max();

// - the minimum of the minimax values of the subtrees, if maximise is false

else return children.Min();

} // end method Minimax

} // end class Tree

private class Forest

{

public Tree first; // first tree

public Forest rest; // remaining trees

// create a single-node tree for each piece of data and link them together

public Forest(int[] nodeData)

{

first = new Tree(nodeData[0]);

if (nodeData.Length > 1)

{

rest = new Forest(nodeData, 1);

}

else rest = null;

} // end constructor

public Forest(int[] nodeData, int start)

{

first = new Tree(nodeData[start]);

if (nodeData.Length - start > 1)

{

rest = new Forest(nodeData, start + 1);

}

else rest = null;

} // end constructor

// determine the maximum of the minimax values of the trees in the forest

public int Max()

{

// this method returns the maximum of the minimax values of the trees in the forest

int max = first.Minimax(false);

if (rest != null) max = Math.Max(first.Minimax(false), rest.Max());

return max;

} // end method Max

// determine the minimum of the minimax values of the trees in the forest

public int Min()

{

// this method returns the minimum of the minimax values of the trees in the forest

int min = first.Minimax(true);

if (rest != null) min = Math.Min(first.Minimax(true), rest.Min());

return min;

} // end method Min

} // end class Forest

} // end class Minimax
``````
0
Question by:Mpencili
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LVL 4

Accepted Solution

Busac earned 1000 total points
ID: 22676691
So which part you don't know how to do? (And what game are we talking about anyway? :-))
0

Author Comment

ID: 22676777
This is a tic-tac-toe game.
The required outcome is fully explained in text form accompanying the code.
Cheers.
0

Author Closing Comment

ID: 31503791
Fake website
0

LVL 4

Expert Comment

ID: 22748317
Umm, my previous comment wasn't intended to be a solution to this problem.
0

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