Python中使用Prim算法求最小生成树

import sys

class Graph(object):
    def __init__(self, vertices):
        self.vertices = vertices
        self.graph = [[0 for column in range(vertices)] for row in range(vertices)]

    def printMST(self, parent):
        print("Edge \tWeight")
        for i in range(1, self.vertices):
            print(parent[i], "-", i, "\t", self.graph[i][ parent[i] ])

    def minKey(self, key, mstSet):
        min = sys.maxsize

        for v in range(self.vertices):
            if key[v] < min and mstSet[v] == False:
                min = key[v]
                min_index = v

        return min_index

    def primMST(self):
        key = [sys.maxsize] * self.vertices
        parent = [None] * self.vertices # Array to store constructed MST
        key[0] = 0
        mstSet = [False] * self.vertices

        parent[0] = -1  # First node is always the root of

        for cout in range(self.vertices):

            u = self.minKey(key, mstSet)

            mstSet[u] = True

            for v in range(self.vertices):

                if self.graph[u][v] > 0 and mstSet[v] == False and key[v] > self.graph[u][v]:

                        key[v] = self.graph[u][v]
                        parent[v] = u

        self.printMST(parent)

g = Graph(5)
g.graph = [[0, 2, 0, 6, 0],
            [2, 0, 3, 8, 5],
            [0, 3, 0, 0, 7],
            [6, 8, 0, 0, 9],
            [0, 5, 7, 9, 0],
           ]

g.primMST()