intest - enormous input test

problem

The purpose of this problem is to verify whether the method you are using to read input data is sufficiently fast to handle problems branded with the enormous Input/Output warning. You are expected to be able to process at least 2.5MB of input data per second at runtime.

Input: The input begins with two positive integers n k (n, k<=107). The next n lines of input contain one positive integer ti, not greater than 109, each.

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

Example
Input:
7 3
1
51
966369
7
9
999996
11

Output:
4

Source

fast io with stdin

Definitely one of the most intersting/valuable ideas this far into the book has to be the use of sys’ stdin for fast io. According to the authors, it offers 4x speedup over python’s input().

And for a further 2x improvement, just read the whole of the inputs in a single system call using os.read() instead! You just need a sense of the upper bound size M of the file you want to read.

solution

Putting those ideas to use, gives us:

from sys import stdin, stdout

def readint():
    return int(stdin.readline())

def read_inputs():
    n, k = stdin.readline().split()
    return int(n), int(k)

def are_divisible(n: int, k: int):
    count = 0
    for _ in range(n):
        t = readint()
        if t % k == 0:
            count += 1
    stdout.write(str(count))

if __name__ == "__main__":
    n, k = read_inputs()
    are_divisible(n, k)