Homework 11 Due Sun 1114 Mon 1115 MT

Homework 11 • Due Sun. , 11/14 Mon. , 11/15 ( MT sections ) at midnight ( WTh sections ) • Problems http: //www. cs. hmc. edu/courses/2004/fall/cs 5/week_11/homework. html • Tutors available Fri. , Sat. afternoons Lac Lab and Parsons (1 -4) Sunday evenings Lac Lab and Parsons (8 -12) Monday evenings Lac Lab and Parsons (8 -12) names and hours linked from the CS 5 Syllabus

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Player Picture of a Player object Player player. For. X char checker int lookahead int tiebreak. Type Player(char ch, int lk, int tbk) char get. Checker() char me() void print. Scores() char opp() int go(Board b) double evaluate(Board b) double[] ply 0, 1, 2, 3, 4, N(Board b) double[] ply. Human(Board b) … int breaktie(double[] s)

Problem 1: Methods to write New Methods class Board public void remove. Move(int c) public void clear() public boolean is. Over() Methods class Player small methods: constructor, me(), you(), print. Scores public double[] find. Scores(Board b) public double[] ply 0(Board b) (ply 1, ply 2, ply 3, ply 4, (ply. N) ) extra credit public int ply. Human(Board b) public int breaktie(double[] s) public double evaluate(Board b) public double tournament. Evaluate(Board b) extra credit no “go”

Problem 1: Outline create an array of 7 doubles s ply find the score for each column 50 main while 50 0 100 -1 s find the maximum score max = 100 break ties (right, left, random) return a single move 3 (column 3) tie bkr

Hw 10 Hw 11 class CS 5 App { public static void main(String[] args) { H. pl("Hi! Welcome to Connect 4. . . "); int R = H. ni(); int C = H. ni(); 6 7 Changes Board b = new Board(R, C); Player px = new Player(‘X’, lk, tb); Player po = new Player(‘O’, lk, tb); char player = 'X'; Player player = px; while (true) { b. print(); int c = H. ni(); // gets next move b. add. Move(c, player); player. me() if (b. wins. For(player)) break; player. me() if (player == 'X') player = '0'; else player = 'X'; } // end of while } } if (player == px) player = po; else player = px;

Details ‘X’ ply tiebreaker Details ‘O’ ply tiebreaker Player px Player po Player px = new Player(‘X’, lk, tb); Player po = new Player(‘O’, lk, tb); Player player = px; if (player == px) player = po; else player = px;

Choosing a move 1) Find scores at appropriate lookahead… ply 0: 0 ply of lookahead ply 1: 1 ply of lookahead ply 2, 3, 4: 2, 3, 4 ply of lookahead ply. Human: ask the user find. Scores chooses one of these methods to run 2) Print the scores. print. Scores: prints the scores to each column 3) Break ties to determine the next move. breaktie: chooses ONE maximum score

find. Scores returns the appropriate set of seven scores char checker int lookahead class Player { public double[] find. Scores(Board b) { int tiebreak. Type

class Player { // returns a set of scores! // with the user choosing a col public double[] ply. Human(Board b) { ply. Human • need to prompt for input • need a valid score • need to support “hints” s ? ? c 0 1 2 3 4 5 6

class Player { public double[] ply 0(Board b) { double[] s = new double[7]; for (int c=0 ; c<7 ; ++c) { if (b. allows. Move(c)) { s[c] = } else s[c] = } return s; } ply 0

Looking ahead … 0 ply: random (but legal) choice of move ! 1 ply: X’s move 2 ply: X’s move 3 ply: X’s move (1) player will win (2) player will avoid losing (3) player will set up a win by forcing the opponent to avoid losing

2 -ply scores for O col 0 col 1 col 2 col 3 col 4 col 5 col 6 1 -ply scores for X col 0 col 1 col 2

3 -ply scores for X col 0 col 1 col 2 col 3 col 4 col 5 col 6 2 -ply scores for O col 0 col 1 col 2

‘X’ ‘O’ new‘X’ Choosing the best move b (1) For each possible move (2) Create new boards (3) Evaluate and return the seven scores received 100. 0 50. 0 Col 6 Col 0 Col 5 Col 1 Col 2 Col 3 Col 4 50. 0 100. 0

class Player { public double[] ply 1(Board b) { double[] s = new double[7]; for (int c=0 ; c<7 ; ++c) { if (b. allows. Move(c)) { This is copied directly from the ply 0 code! s[c] = evaluate(b); } else s[c] = -1. 0; } return s; } ply 1

evaluate 100. 0 for a win 50. 0 for a “tie” 0. 0 for a loss -1. 0 for an invalid move class Player not possible in evaluate! { // returns the appropriate score for b // remember: all of Player’s methods are available public double evaluate(Board b) { if ( ) return 100. 0; else if ( return 0. 0; else return 50. 0; ) Improvements? Write tournament. Evaluate for Ex. Cr. !

class Player { public double[] ply 2(Board b) { double[] s = new double[7]; for (int c=0 ; c<7 ; ++c) { if (b. allows. Move(c)) { This is copied directly from the ply 0 code! s[c] = evaluate(b); } else s[c] = -1. 0; } return s; } ply 2

class Player { // returns a column to move // public int breaktie(double[] s) { breaktie s 0 50 50 -1 -1 c 0 1 2 3 4 5 6

class Board { // removes a move from col c // public void remove. Move(c) { remove. Move this. data 0 X O O X X 1 X O O X X 2 X O O X X 3 X O O X X 4 X O O X X 5 X O O X X 0 1 2 3 row column 4 5 6

Good luck on this!

double[] s = player. find. Scores(b); player. print. Scores(s); int c = player. breaktie(s);