Max Sum Path | Python Fiddle

from Queue import Queue
class Vertex:
    def __init__(self, num, i):
        self.num = num
        self.succeed = []
        self.prev = []
        self.code = i

def __contains__(self, other):
        if self.code is other.code:
            return True
        else:
            return False

def MaximumPathSum(filename):
    explored = set([])  # store explored edges
    path = []  # store path
    sumpath = []  # store sum of a vertex
    open = Queue() # store the unexplored vertex
    src = Graph(filename)
    open.put(src)
    path.append(src)
    sumpath.append(src.num)
    v = src

while not open.empty():
        v = path[maxVert(explored, sumpath, path)] # find the vertice with the max value
        print "bla"
        for s in v.succeed:
            if s not in open and s not in explored:
                open.put(s)
                path.append(s)
                sumpath.append(0)
                s.prev.append(v)

if len(s.prev) != 0:
                for pred in s.prev:
                    sum = s.num + sumpath[path.index(pred)]
                    if sum > sumpath[path.index(s)]:
                        sumpath[path.index(s)] = sum

explored.add(v)
        open.get()

return max(sumpath)

def maxVert(explored, sumpath, path):
    index = 0;
    sum = -1
    for i in range(0, len(sumpath)) :
        if path[i] not in explored  and  sumpath[i] > sum:
            sum = sumpath[i]
            index = i
    return index

def Graph(filename):
    file = open(filename, "r")
    src = None
    i = 1
    for line in file:
        v = Vertex(int(line.split()[0]), i)
        src = v
        i+=1
        break

prev = [src]

for line in file:
        nums = line.split()
        vertexes = []
        for num in nums:
            v = Vertex(int(num), i)
            vertexes.append(v)
            i += 1

for v in prev:
            for i in range(0, len(vertexes)-1):
                successor =  [vertexes[i], vertexes[i+1]]
            v.succeed = successor
        prev = vertexes

return src

print MaximumPathSum("Problem18.txt")

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