```python
# 二维数组转换与字符的相互转换
# test = [[1, 2, 300], [5, 4, 5]]
def num_to_str(num):
string = ''
for i in num:
string = string + '/'
for j in i:
string = string + str(j)+','
return string
# a = num_to_str(test)
# print(a)
def str_to_num(string):
num = [[]]
count = 0
str1 = '0'
flag = True
for index in string:
if index == '/':
num.append([])
count += 1
elif index == ',':
# print(str1)
str1 = int(str1)
# print(str1)
num[count].append(str1)
str1 = '0'
else:
str1 = str(str1)
str1 += index
# print(num)
num = num[1:]
return num
# a = str_to_num(a)
# print(a)