lords-of-the-ring.py

#language = python3

def lordOfTheRing(A):
	stack = []
	for i in range(len(A)-1,-1,-1):
		# condition for mainintain final 2 players in ring
		if i==0 and len(stack)==1:
			stack.append(A[0])
			continue
		# inital condition
		if not stack:
			stack.append(A[i])
		else:
			# when negative potential => pick next left player
			if i>0 and A[i]<0:
				if abs(A[i-1])==abs(A[i]):
					continue
				elif abs(A[i-1])>abs(A[i]): # winner will be left player
					w=A[i-1] 
				else: # current player will win
					w = A[i]
			else: # positive potential -> check right player -> check top of stack
				w = A[i]
				
			top = stack[-1] # see who's the existing winner 
			if w>=0: # if winner is positive potential then he will fight for right (top of stack)
				stack.pop()
				stack.append(w if abs(w)>abs(top) else top)
			elif abs(w)==abs(top): # disqualify both
				stack.pop()
			else:
				stack.append(w)
					
	# since we need either two lords of ring or none | reverse the stack to maintain order
	return stack[::-1] if len(stack)==2 else []
				
print(lordOfTheRing([1,1,1,1,6,1,1]))
print(lordOfTheRing([5,10,-5]))
print(lordOfTheRing([1,2,-3,5,-4,6]))