python广度优先搜索得到两点间最短路径

import numpy as np

ini_matrix = [
     [0, 1, 1, 0, 1],
     [1, 0, 0, 1, 0],
     [1, 0, 0, 0, 1],
     [0, 1, 0, 0, 0],
     [1, 0, 1, 0, 0]
     ]


def bfs(matrix_para, start_point_para, end_point_para):
  """
  广度优先搜索
  :param matrix_para 图
  :param start_point_para 起点
  :param end_point_para 终点
  :return: 返回关联度
  """
  matrix = matrix_para
  start_point = start_point_para
  end_point = end_point_para

  vertex_num = len(matrix) # 顶点个数

  que = np.zeros(vertex_num, dtype=np.int) # 队列， 用于存储遍历过的顶点
  book = np.zeros(vertex_num, dtype=np.int) # 标记顶点i是否已经被访问，1表被访问，0表未被访问

  point_step_dict = dict() # key:点，value:起点到该点的步长

  # 队列初始化
  head = 0
  tail = 0

  # 从起点出发，将起点加入队列
  que[tail] = start_point # 等号右边为顶点号（起点）
  tail += 1
  book[start_point] = 1 # book[i] i为顶点号

  while head<tail:
    cur = que[head]
    for i in range(vertex_num):
      # 判断从顶点cur到顶点i是否有边，并判断顶点i是否已经被访问过
      if matrix[cur][i] == 1 and book[i] == 0:
        que[tail] = i # 将顶点i放入队列中
        tail += 1 # tail指针往后移
        book[i] = 1 # 标记顶点i为已经访问过
        point_step_dict[i] = head + 1 # 记录步长
      if tail == vertex_num: # 说明所有顶点都被访问过
        break
    head += 1

  for i in range(tail):
    print(que[i])

  try:
    relevancy = point_step_dict[end_point]
    return relevancy
  except KeyError: # 捕获错误，如果起点不能到达end_point，则字典里没有这个键，返回None
    return None

result = bfs(ini_matrix, 1, 4)
print("result:", result)

import numpy as np

ini_matrix = [
     [0, 1, 1, 0, 1],
     [1, 0, 0, 1, 0],
     [1, 0, 0, 0, 1],
     [0, 1, 0, 0, 0],
     [1, 0, 1, 0, 0]
     ]


def bfs(matrix_para, start_point_para, end_point_para):
  """
  广度优先搜索
  :param matrix_para 图
  :param start_point_para 起点
  :param end_point_para 终点
  :return: 返回关联度
  """
  matrix = matrix_para
  start_point = start_point_para
  end_point = end_point_para

  vertex_num = len(matrix) # 顶点个数

  que = np.zeros(vertex_num, dtype=np.int) # 队列， 用于存储遍历过的顶点
  book = np.zeros(vertex_num, dtype=np.int) # 标记顶点i是否已经被访问，1表被访问，0表未被访问

  point_step_dict = dict() # key:点，value:起点到该点的步长

  # 队列初始化
  head = 0
  tail = 0

  # 迭代次数
  count = 0

  # 从0号顶点出发，将0号顶点加入队列
  que[tail] = start_point # 等号右边为顶点号（起点）
  tail += 1
  book[start_point] = 1 # book[i] i为顶点号

  while head<tail:
    flag = False # 用flag标识结点i是否周围都是被访问过的
    cur = que[head]
    for i in range(vertex_num):
      # 判断从顶点cur到顶点i是否有边，并判断顶点i是否已经被访问过
      if matrix[cur][i] == 1 and book[i] == 0:
        que[tail] = i # 将顶点i放入队列中
        tail += 1 # tail指针往后移
        book[i] = 1 # 标记顶点i为已经访问过
        point_step_dict[i] = count + 1 # 记录步长
        flag = True
      if tail == vertex_num: # 说明所有顶点都被访问过
        break
    if flag:
      count += 1
    head += 1

  for i in range(tail):
    print(que[i])

  try:
    relevancy = point_step_dict[end_point]
    return relevancy
  except KeyError:
    return None

result = bfs(ini_matrix, 3, 4)
print("result:", result)