将整数的 .txt 拆分为列表 Python

Question

I am considering doing the Google Hash Code , but am running into some issues on the practice problems ! The problem is order a number of pizza slices without going over the limit. The input gives you the different quantities of slices for each type. This is the c_medium.in input file:

4500 50
7 12 12 13 14 28 29 29 30 32 32 34 41 45 46 56 61 61 62 63 65 68 76 77 77 92 93 94 97 103 113 114 114 120 135 145 145 149 156 157 160 169 172 179 184 185 189 194 195 195

To determine my options for sizes, I am using this code:

file = open('c_medium.in','r')
raw_pizza_types = file.readline(2)
pizza_types = raw_pizza_types.split()
print(pizza_types)
max = file.readline(1)
def solution() -> None:
  #pizza_types = [int(i) for i in pizza_types] # will loop through strings and convert them to ints 
  pass

This code should print out a list with the number of slices on different pies, but instead simply prints out ['45'] . Can anyone help me fix this?

Answer 1

the parameter in readline() indicates size to be read, not the number of lines to be read. So you're telling it to read in only the first two characters, which are 45 and then stop.

What you want to be doing is using the command readlines() , which by default reads in all lines as a list. You would then just have to process the data out of the list. I would recommend something along the lines of:

file = open('filename', 'r')
raw_pizzas = file.readlines()
slices = []
for p in raw_pizzas:
    for s in p.split():
        slices.append(s)
print(slices)

please note that this is meant as more of pseudocode, I have not tested to make sure it works as written.

Answer 2

The readline method's parameter is size and does not read the second line, which I'm assuming is what you want to do. File-handles are iterators, and can't go back to a previous line unless you seek . So I would read in your variables in the order that they appear in the file:

# the with statement is the pythonic way to open files
# since you don't need to remember to close them
with open('c_medium.in','r') as fh:
    # read the first line to max, but max itself is a function
    # so we will name it something else
    maximum_slices = [int(x) for x in next(fh).split()]

    # this will split the second line on any whitespace character
    pizza_types = next(fh).split()

Your list comprehension should be perfectly sufficient after that. I am also assuming that the maximum_slices should also be a list of integers