处理python中的大型输入 [英] Handling large inputs in python

问题描述

几个月前我开始学习编程，最近才发现 codechef 。

问题是对于使用大量输入的问题我的代码alwaqys超出时间限制。我甚至无法使输入测试工作。

I started learning programming a few months ago and just recently found codechef.
The problem is that on problems that use large amounts of input my code alwaqys exceehe time limit. I can't even seem to make the input test work.

来自codechef的说明：

Description from codechef:

输入

Input

输入以两个正整数nk（n，k <= 10 ^ 7）开始。下一个
n输入行包含一个正整数ti，每个不大于
10 ^ 9。

The input begins with two positive integers n k (n, k<=10^7). The next n lines of input contain one positive integer ti, not greater than 10^9, each.

输出

写一个整数输出，表示有多少整数ti是
可被k整除。

Write a single integer to output, denoting how many integers ti are divisible by k.

这是代码：

n, t = [int(x) for x in input().split()]
c = 0
for i in range(n):
    if not int(input()) % t:
        c += 1
print(c)

我不确定我错过了什么。我怎样才能更快地处理这个？

I'm not sure what I'm missing. How can I handle this faster?

推荐答案

这应该是一个评论，但无论如何。

This should really be a comment, but anyway.

请注意，此处有一个可接受的Python 2解决方案，运行时为45.77s ，所以它显然是可能的。我认为你是Python 3缓慢I / O的受害者（看起来他们正在使用3.1.2）。在一个200万行输入文件（它没有任何可分割的数字）：当有很多时没有太大区别），在你的代码版本修改为与2和3兼容时，我得到：

Note that there's an accepted Python 2 solution here, with runtime 45.77s, so it's clearly possible. I think you're a victim of Python 3's slow I/O (looks like they're using 3.1.2). On a two million line input file (which happens not to have any numbers which are divisible): there's not much difference when there are a lot), on a version of your code modified to be compatible with 2 and 3, I get:

~/coding$ time python2.6 enormread.py < sample.txt 
0

real    0m3.971s
user    0m3.712s
sys 0m0.256s
~/coding$ time python2.7 enormread.py < sample.txt 
0

real    0m2.637s
user    0m2.428s
sys 0m0.204s
~/coding$ time python3.2 enormread.py < sample.txt 
0

real    0m10.412s
user    0m10.065s
sys 0m0.344s
~/coding$ time ~/sys/Python-3.3.0a2/python enormread.py < sample.txt 
0

real    0m6.776s
user    0m6.336s
sys 0m0.436s
~/coding$ time pypy enormread.py < sample.txt 
0

real    0m2.211s
user    0m1.948s
sys 0m0.028s

抛出@ agf的（对于sys.stdin [.buffer]中的行，总和（不是int（行）％t））进入组合：

To throw @agf's (sum(not int(line) % t for line in sys.stdin[.buffer])) into the mix:

~/coding$ time python2.7 enormfast.py < sample.txt 
0

real    0m1.454s
user    0m1.436s
sys 0m0.016s
~/coding$ time python3.2 enormfast.py < sample.txt 
0

real    0m2.243s
user    0m2.228s
sys 0m0.012s

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