如何跳过（原始）输入的一行，Python 3

Question

I am completing the following HackerRank challenge . I am fed the following input:

4
2 4 5 9
4
2 4 11 12

Let's say though I just want the 2nd and 4th lines of input (and assume all input will look like this). At the moment I'm implementing a hackneyed solution:

seta = set()
setb = set()
delete = input()
seta = input().split()
delete = input()
setb = input().split()

I don't use delete later in the program. Is there a better, more exact and concise way forward?

Answer 1

Loop over the sys.stdin object ; it is a regular file and supports iteration. You can use an itertools.islice() object to skip every second line:

import sys
from itertools import islice

second_lines = islice(sys.stdin, None, None, 2)
seta = set(map(int, next(second_lines).split()))
setb = set(map(int, next(second_lines).split()))