Problem: You are given N real values A_1, A_2, \ldots, A_N. Compute the number of pairs of indices (i, j) such that i < j and the product A_i \cdot A_j is integer.

Submission attempts (in order):
# coding: utf-8
import sys
#from operator import itemgetter
sysread = sys.stdin.buffer.readline
read = sys.stdin.buffer.read
#from heapq import heappop, heappush
#from collections import defaultdict
sys.setrecursionlimit(10**7)
import math
#from itertools import product, accumulate, combinations, product

#import numpy as np
#from copy import deepcopy
#from collections import deque

INF = 1 << 50



def run():
    N, *A = map(float, read().split())
    M = [[0] * 19 for _ in range(19)]
    
    minus = 0
    for i, a in enumerate(A):
        if a == int(a):
            minus += 1
        a *= 10 ** 9
        a = int(a)
        
        #print(a)
        f2 = 0
        f5 = 0
        while True:
            if not a % 2:
                f2 += 1
                a = a // 2
            else:
                break
        while True:
            if not a % 5:
                f5 += 1
                a = a // 5
            else:
                break
        A[i] = (min(f2, 18), min(f5, 18))
        M[min(f2, 18)][min(f5, 18)] += 1

        
    #print(A)
    #for m in M:
    #    print(m)
    
    for i in range(18, 0, -1):
        for j in range(18, -1, -1):
            M[i-1][j] += M[i][j]
    
    for i in range(18, -1, -1):
        for j in range(18, 0, -1):
            M[i][j-1] += M[i][j]

    ans = 0
    for f2, f5 in A:
        ans += M[max(18-f2, 0)][max(18-f5, 0)]
        
    print((ans-minus)//2)
    
    for m in M:
        print(m)


if __name__ == "__main__":
    run()

# coding: utf-8
import sys
#from operator import itemgetter
sysread = sys.stdin.buffer.readline
read = sys.stdin.buffer.read
#from heapq import heappop, heappush
#from collections import defaultdict
sys.setrecursionlimit(10**7)
import math
#from itertools import product, accumulate, combinations, product

#import numpy as np
#from copy import deepcopy
#from collections import deque
from decimal import Decimal

INF = 1 << 50



def run():
    N = int(sysread())
    A = [Decimal(input()) for _ in range(N)]
    M = [[0] * 19 for _ in range(19)]
    #print(A)
    minus = 0
    
    MULT = 10 ** 9
    for i, a in enumerate(A):
        if a == int(a):
            minus += 1
        a *= MULT
        a = int(a)
        
        #print(a)
        f2 = 0
        f5 = 0
        while True:
            if not a % 2:
                f2 += 1
                a = a // 2
            else:
                break
        while True:
            if not a % 5:
                f5 += 1
                a = a // 5
            else:
                break
        A[i] = (min(f2, 18), min(f5, 18))
        M[min(f2, 18)][min(f5, 18)] += 1

        
    #print(A)
    #for m in M:
    #    print(m)
    
    for i in range(18, -1, -1):
        for j in range(18, -1, -1):
            if i > 0:
                M[i-1][j] += M[i][j]
                
    for i in range(18, -1, -1):
        for j in range(18, -1, -1):
            if j > 0:
                M[i][j-1] += M[i][j]

    ans = 0
    for f2, f5 in A:
        ans += M[max(18-f2, 0)][max(18-f5, 0)]
        
    print((ans-minus)//2)
    
    #for m in M:
    #    print(m)
    

if __name__ == "__main__":
    run()

Verdicts: Wrong Answer

Accepted