def depthLimitedSearch(pegSolitaireObject, maxDepth):
#Check if the current state is goal state or not
if pegSolitaireUtils.isGoalState(pegSolitaireObject.gameState):
return True
#If current state is already explored, it will not explore it furthur and return
if pegSolitaireUtils.isAlreadyExplored(pegSolitaireObject.gameState):
return
#if depth reached is zero, goal can't be find with these moves and it backtracks
if maxDepth == 0:
return
#Check for all pegs in the peg board in all direction for next game state
for i in xrange(7):
for j in xrange(7):
if pegSolitaireObject.gameState[i][j] == 1:
for direction in all_directions:
#check valid move
if pegSolitaireObject.is_validMove((i,j),direction):
#Save game state in another state variable, so that we can backtrack if our next move eventually fails
parentObject = pegSolitaireUtils.game("game.txt")
parentObject.gameState = pegSolitaireUtils.copyGameState(pegSolitaireObject)
#Get next valid move state
pegSolitaireObject.getNextState((i,j),direction)
#Recursively call function with next valid move and depth-1
result = depthLimitedSearch(pegSolitaireObject, maxDepth-1)
#If the above exploration fails it will return to its initial game state (backtrack)
if result == None:
pegSolitaireUtils.restoreInitialState(pegSolitaireObject,parentObject.gameState)
#If Goal state is reached, it computes the trace and return true
if result == True:
#Get next move position for computing trace
newpos = pegSolitaireObject.getNextPosition((i,j), direction)
pegSolitaireObject.trace.insert(0,newpos)
pegSolitaireObject.trace.insert(0,(i,j))
return True
return
def aStarOne(pegSolitaireObject):
#################################################
# Must use functions:
# getNextState(self,oldPos, direction)
#
# we are using this function to count,
# number of nodes expanded, If you'll not
# use this grading will automatically turned to 0
#################################################
#
# using other utility functions from pegSolitaireUtility.py
# is not necessary but they can reduce your work if you
# use them.
# In this function you'll start from initial gameState
# and will keep searching and expanding tree until you
# reach goal using A-Star searching with first Heuristic
# you used.
# you must save the trace of the execution in pegSolitaireObject.trace
# SEE example in the PDF to see what to return
#
#################################################
intialStartingState = pegSolitaireUtils.copyGameState(pegSolitaireObject)
#This Queue would keep elements in increasing order of priority. This priority is decided by heuristic value.
heapQueue = Queue.PriorityQueue()
#Keep a hash of all explored states to prevent exploration of repeated states.
pegSolitaireUtils.executedStates = set()
#ParentStates would include a dictionary to map children nodes to its parent node along with the direction it arrived from.
#This would help us to compute trace.
parentStates = {}
#Insert the first element in the Priority Queue and run a loop until either
#1. Goal is reached.
#2. All states are explored.
heapQueue.put((0,pegSolitaireObject.gameState))
parentStates[pegSolitaireUtils.stateToString(pegSolitaireObject.gameState)] = (None,None)
while not heapQueue.empty():
currentNodeState = (heapQueue.get())[1]
#If current state is already explored, get the next state from the Queue.
if pegSolitaireUtils.isAlreadyExplored(currentNodeState):
if heapQueue.empty():
return False;
currentNodeState = (heapQueue.get())[1]
#If the current state is goal state, compute the trace and return True.
if pegSolitaireUtils.isGoalState(currentNodeState):
pegSolitaireUtils.computeTrace(parentStates,pegSolitaireUtils.stateToString(currentNodeState),pegSolitaireObject)
return True
#Back up of the parent node.
initialState = copy.deepcopy(currentNodeState)
pegSolitaireObject.gameState = currentNodeState
#Get list of valid moves from the current game state.
nextValidMoves = pegSolitaireUtils.setValidMoves(pegSolitaireObject)
for nextMove in nextValidMoves:
#Get next state of the game based on the position of current node and direction.
pegSolitaireObject.getNextState((nextMove[0],nextMove[1]),nextMove[2])
#Set parent for the current state.
parentStates[pegSolitaireUtils.stateToString(pegSolitaireObject.gameState)] = (pegSolitaireUtils.stateToString(initialState),nextMove)
#Put the node and the its f(n) value in the queue [f(n) = g(n) + h(n)]
heapQueue.put((pegSolitaireUtils.funcFforAStarOne(intialStartingState,pegSolitaireObject),pegSolitaireUtils.copyGameState(pegSolitaireObject)))
#Restore original state for next iteration.
pegSolitaireUtils.restoreInitialState(pegSolitaireObject,initialState)
pegSolitaireObject.trace.append("GOAL NOT FOUND")
return False