2.2 PCW Breadth First Search

# [INSERT CODE HERE] Initial state
state = 1 

# [INSERT CODE HERE] Define the goal here
goal = 1024

# Frontier
from collections import deque
frontier = deque([state])

# Step counter
steps = 0


# Breadth-first search algorithm (continue while there are nodes in the frontier)
while frontier:
    #increment counter
    steps += 1 #debatable. you can add 2 steps or 1 depending on your interpretation
    res = frontier.popleft() 
    
    #start generating children right away then test for the condition on each child
    #generate two children and add them to end of frontier. 
    if (res*2 == goal or res*2+1 == goal):
        break
    frontier.extend([res*2, res*2+1])    
    
    
# [INSERT CODE HERE] Find the length of the frontier by changing the line below.
frontier_size = len(frontier)
    

print("Breadth-first search terminated after %d steps\n" % steps)
print("Size of frontier at termination is %d" % frontier_size)

Result depending on step increment. If the increment is one per loop result is 512, and 511 frontier size. 512 frontier size can occur depending on where you apply popleft()