coding_challenge_1c.py

def dirReduc(arr):
    if(len(arr) <= 1): # short circuit
        return arr
    
    directions = {
        "NORTH" : "SOUTH" , 
        "SOUTH" : "NORTH" , 
        "WEST" : "EAST" , 
        "EAST" : "WEST" 
    }
    
    output = []
    
    i = 0
    while(i < len(arr)):
        move = arr[i]
        
        try:
            next_move = arr[i + 1]
        except IndexError:
            next_move = None
        
        if (next_move == directions[move]):
            i += 2
        else:
            output.append(move)
            i += 1
    
    if(len(output) == len(arr)): # base case of no redudant directions
        return output
    else:
        return dirReduc(output) # recursive call

# testing - should return ["WEST"]
dirReduc(["NORTH", "SOUTH", "SOUTH", "EAST", "WEST", "NORTH", "WEST"])
# Oh, yeah! ["WEST"]