lab12 & project

from numpy import inf

graph = {

    'A': {'E': 3, 'B': 7, 'F': 2, 'D': 3},

    'B': {'E': 1, 'A': 7, 'F': 2, 'C': 5},

    'C': {'B': 5, 'F': 3, 'D': 6},

    'D': {'C': 6, 'F': 1, 'A': 3},

    'E': {'B': 1, 'A': 3},

    'F': {'C': 3, 'D': 1, 'A': 2, 'B': 2}

}

costs = {'A': inf, 'B': inf, 'C': inf, 'D': inf, 'E': inf, 'F': inf}

parents = {}

def search(source, target, graph, costs, parents):

    costs[source] = 0

    nextNode = source

    while nextNode != target:

        for neighbor in graph[nextNode]:

            if graph[nextNode][neighbor] + costs[nextNode] < costs[neighbor]:

                costs[neighbor] = graph[nextNode][neighbor] + costs[nextNode]

                parents[neighbor] = nextNode

            del graph[neighbor][nextNode]

        del costs[nextNode]

        nextNode = min(costs, key=costs.get)

    return parents

# result = search('A', 'C', graph, costs, parents)

def backpedal(source, target, searchResult):

    node = target

    backpath = [target]

    path = []

    while node != source:

        backpath.append(searchResult[node])

        node = searchResult[node]

    for i in range(len(backpath)):

        path.append(backpath[-i - 1])

    return path

# print('parent dictionary={}'.format(result))

#

# print('ideal path={}'.format(backpedal('A', 'C', result)))

def router_table(src, dst):

    costs_tmp = {'A': inf, 'B': inf, 'C': inf, 'D': inf, 'E': inf, 'F': inf}

    graph = {

    'A': {'E': 3, 'B': 7, 'F': 2, 'D': 3},

    'B': {'E': 1, 'A': 7, 'F': 2, 'C': 5},

    'C': {'B': 5, 'F': 3, 'D': 6},

    'D': {'C': 6, 'F': 1, 'A': 3},

    'E': {'B': 1, 'A': 3},

    'F': {'C': 3, 'D': 1, 'A': 2, 'B': 2}

}

    parents = {}

    result = search(src, dst, graph, costs_tmp, parents)

    path = backpedal(src, dst, result)

    next_hop = path

    return next_hop

# print forwarding table

# the value of each key is the link that the packet should go

def print_forward_table(src):

    fwd_table = {'A': 0, 'B': 0, 'C': 0, 'D': 0, 'E': 0, 'F': 0}

    del fwd_table[src]

    for dst in fwd_table:

        link_array = [src]

        table = router_table(src,dst)

        link_array.append(table[1])

        print(table)

        fwd_table[dst] = link_array

    return fwd_table

print(print_forward_table("A"))

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