在python3中快速从txt文件中读取二维列表

Question

I need to write a program in python that reads a 2d list from a txt file and then does some stuff in certain elapsed time (ie 2 seconds).

3 3
ULR
RRL
UUD

This is how the txt file is inside.

with open(argv[1]) as f:
n,m=f.read().split()
n=int(n)
m=int(m)
a=[[char for char in line]for line in f]  

And this is the code I use to parse the data into a 2d list.
My issue is that its too slow. The main algorithm of the program has a time complexity of O(n^2) and I have written the same program in c to test the same inputs. In order to successfully terminate with an 999x999 array as input, the c program takes about 5 seconds, while the python one takes a lot more than 10. Since the algorithm is effectively the same, my next thought is that my way of passing data from the file into a 2d list in python is to blame.
Appreciate your input:).

Answer 1

I think this might be faster:

with open("filename.txt", encoding="UTF-8") as ifile:
    m, n = ifile.readline().split()
    arr2d = list(map(list, ifile.readlines()))