a = [[1,2],[2,0]]
b = [2,0]
aa = a[1]
# at this point, b = [2,0] and aa = [2,0]
# but aa == b returns False
 
# aa[0] == b[0] returns True
# aa[1] == b[1] returns True

a = [(1,2),(2,0)]
b = (2,0)
aa = a[1]
# now aa == b returns True
 
#alternatively, though probably slightly less efficient, you could convert the coordinates to tuples at the point of comparison
# tuple(aa) == tuple(b) would return True in the first example code.

a = [ [0,1], [0,2], [1,2] ]
b = [0, 2,]
c = [2, 0]
 
if b in a:
   print "b found"
else:
   print "b not found"
 
if c in a:
   print "c found"
else:
   print "c not found"

#n is going to be equal to 4 for this queens problem.
n = 4
 
#Assigning the empty list to initialState.
initialState = []
 
#Making an allDirections list.
allDirections = [[-1,0],[1,0],[0,-1],[0,1],[-1,-1],[-1,1],[1,-1],[1,1]]
 
#declare the list 'state' which represents the number of non threatening
#queens that have been placed on the board.
state = []
 
def goal(state):
	if (len(state) == n):
		return True
	else:
		return False
 
#defining allRules list which the contents of which will be created in next function.
allRules = []
#defining all the rules for an nxn board. assigning these rules to allRules
def makeRules(n):
	for i in range(1, (n+1), 1):
		for j in range(1, (n+1), 1):
			allRules.append([i,j])
	return
 
#making a rule list. this list will probably be refined in future assignments but it will contain the one rule that is applicable in the current state. for #now we will just make it an empty list.
rule = []
#this function will apply the rule that is in the rule list to the given state, which just appends it to the state list.
def applyRule(rule,state):
	state.append(rule)
	return
 
#returns true if the row or column of 'pos' is out of bounds.
def outOfBounds(pos):
	if ((pos[0] < 1) or (pos[0] > n) or (pos[1] < 1) or (pos[1] > n)):
		return True
	else:
		return False 	
 
#function that will determine which positions queens cannot be placed into because they might eventually run into another queen already on the board.
def blocked(pos,state,direction):
	newpos = [(pos[0]+direction[0]),(pos[1]+direction[1])]
##	for k in range(0, (len(state)), 1):
##		if (newpos == state[k]):
        print "looking for", newpos
        print state, "\n"
        if newpos in state:
			return True
			print "True"
	elif outOfBounds(newpos):
			return False
			print "False"
	else:
			blocked(newpos,state,direction)
 
state = [[1,2],[2,0]]
direction = [1,0]
pos = [1,0]
##
##   added a variable that contains the value returned by the function
result = blocked(pos,state,direction)
if result == True:
   print "position found"
elif result == False:
   print "position not found"
else:               ## "None" (nothing returned)
   print "position added"