text: import math
  import numpy as np
  
  citys = np.loadtxt('data/city_location.txt')
  for i in range(len(citys)):
        for j in range(2):
              citys[i][j]=round(citys[i][j])
  
  dis=[[0 for x in range(len(citys))] for y in range(len(citys))]
  for i in range(len(citys)):
      for j in range(len(citys)):
          dis[i][j]=math.sqrt((citys[i][0]-citys[j][0])**2+(citys[i][1]-citys[j][1])**2)
  