python实现Dijkstra算法的最短路径问题

#!/bin/python
# -*- coding:utf-8 -*-

def dijkstra(graph, startIndex, path, cost, max):
  """
  求解各节点最短路径，获取path，和cost数组，
  path[i] 表示vi节点的前继节点索引，一直追溯到起点。
  cost[i] 表示vi节点的花费
  """
  lenth = len(graph)
  v = [0] * lenth
  # 初始化 path，cost，V
  for i in range(lenth):
    if i == startIndex:
      v[startIndex] = 1
    else:
      cost[i] = graph[startIndex][i]
      path[i] = (startIndex if (cost[i] < max) else -1)
  # print v, cost, path
  for i in range(1, lenth):
    minCost = max
    curNode = -1
    for w in range(lenth):
      if v[w] == 0 and cost[w] < minCost:
        minCost = cost[w]
        curNode = w
    # for 获取最小权值的节点
    if curNode == -1: break
    # 剩下都是不可通行的节点，跳出循环
    v[curNode] = 1
    for w in range(lenth):
      if v[w] == 0 and (graph[curNode][w] + cost[curNode] < cost[w]):
        cost[w] = graph[curNode][w] + cost[curNode] # 更新权值
        path[w] = curNode # 更新路径
    # for 更新其他节点的权值（距离）和路径
  return path

if __name__ == '__main__':
  max = 2147483647
  graph = [
    [max, max, 10, max, 30, 100],
    [max, max, 5, max, max, max],
    [max, max, max, 50, max, max],
    [max, max, max, max, max, 10],
    [max, max, max, 20, max, 60],
    [max, max, max, max, max, max],
    ]
  path = [0] * 6
  cost = [0] * 6
  print dijkstra(graph, 0, path, cost, max)