TrafficLightsSolver

java.lang.Object
- TrafficLightsSolver

public class TrafficLightsSolver
extends java.lang.Object

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`COLS`
`static int`	`GREEN`
`static int[][]`	`lines`
`static int`	`LOSS`
`static int`	`OFF`
`static int`	`RED`
`static int`	`ROWS`
`static int`	`UNKNOWN`
`static int`	`WIN`
`static int`	`YELLOW`

Constructor Summary

Constructors
Constructor and Description
`TrafficLightsSolver(java.lang.String filename)` Create a TwoBitRandomAccessFile large enough to access any Traffic Lights game state (reachable or not).

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`int`	`eval(int[] state)` Given a game state, recursively evaluate the value of that state and all states reachable from it given optimal play, assigning it the value WIN or LOSS.
`boolean`	`isGameOver(int[] state)` Return whether or not the game is over (3 GREEN/YELLOW/RED in a row horizontally, vertically, or diagonally).
`static void`	`main(java.lang.String[] args)` Test code that solves the game and then allows users to play the game with solution information.
`void`	`play()` Play a text-based Traffic Lights game, displaying winning/losing state information as the game progresses.
`void`	`solve()` Starting with the initial game state, recursively evaluate the value of each state given optimal play, assigning each reachable game state to WIN or LOSS.
`static int`	`stateToInt(int[] state)` Convert the state to a unique integer by treating positions a base 4 digits.
`static java.lang.String`	`stateToString(int[] state)` Return a String representation of the given game state.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - ROWS
```
public static final int ROWS
```
    See Also:
    
    Constant Field Values
  - COLS
```
public static final int COLS
```
    See Also:
    
    Constant Field Values
  - OFF
```
public static final int OFF
```
    See Also:
    
    Constant Field Values
  - GREEN
```
public static final int GREEN
```
    See Also:
    
    Constant Field Values
  - YELLOW
```
public static final int YELLOW
```
    See Also:
    
    Constant Field Values
  - RED
```
public static final int RED
```
    See Also:
    
    Constant Field Values
  - UNKNOWN
```
public static final int UNKNOWN
```
    See Also:
    
    Constant Field Values
  - LOSS
```
public static final int LOSS
```
    See Also:
    
    Constant Field Values
  - WIN
```
public static final int WIN
```
    See Also:
    
    Constant Field Values
  - lines
```
public static int[][] lines
```
- Constructor Detail
  - TrafficLightsSolver
```
public TrafficLightsSolver(java.lang.String filename)
```
    Create a TwoBitRandomAccessFile large enough to access any Traffic Lights game state (reachable or not). For a 3 row, 4 column board, the file will have 4^(ROWS*COLS) = 16777216 2-bit entries, and thus be 4^(ROWS*COLS - 1) = 4194304 bytes.
    
    Parameters:
    
    filename - name of binary solution file
- Method Detail
  - play
```
public void play()
```
    Play a text-based Traffic Lights game, displaying winning/losing state information as the game progresses.
  - solve
```
public void solve()
```
    Starting with the initial game state, recursively evaluate the value of each state given optimal play, assigning each reachable game state to WIN or LOSS.
  - eval
```
public int eval(int[] state)
```
    Given a game state, recursively evaluate the value of that state and all states reachable from it given optimal play, assigning it the value WIN or LOSS. If the game is over, since the player changes with each play, the previous player made a play resulting in the three-in-a-row, so the current player evaluates a game over state as a LOSS. If the game is not over and the player has a play to a LOSS state for their opponent, it is evaluated as a WIN state for the player. Otherwise, all plays lead to WIN states for their opponent and it is evaluated as a LOSS state. Any state not yet evaluated has the file value UNKNOWN. After all recursive evaluation is complete any remaining UNKNOWN states are unreachable in legal play. For example, one can never legally reach a game state with two disjoint (e.g. parallel) three-in-a-row lines.
    
    Parameters:
    
    state - current state to be evaluated as WIN or LOSS
    
    Returns:
    
    value of state, either WIN or LOSS
  - isGameOver
```
public boolean isGameOver(int[] state)
```
    Return whether or not the game is over (3 GREEN/YELLOW/RED in a row horizontally, vertically, or diagonally).
    
    Parameters:
    
    state - game state
    
    Returns:
    
    whether or not the game is over for the game state
  - stateToInt
```
public static int stateToInt(int[] state)
```
    Convert the state to a unique integer by treating positions a base 4 digits.
    
    Parameters:
    
    state - game state
    
    Returns:
    
    a unique state integer
  - stateToString
```
public static java.lang.String stateToString(int[] state)
```
    Return a String representation of the given game state.
    
    Parameters:
    
    state - game state
    
    Returns:
    
    a String representation of the given game state
  - main
```
public static void main(java.lang.String[] args)
```
    Test code that solves the game and then allows users to play the game with solution information.
    
    Parameters:
    
    args - (unused)

Class TrafficLightsSolver

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

ROWS

COLS

OFF

GREEN

YELLOW

RED

UNKNOWN

LOSS

WIN

lines

Constructor Detail

TrafficLightsSolver

Method Detail

play

solve

eval

isGameOver

stateToInt

stateToString

main