#=========================================================#
#  Multi-digit multiplication time by python with int     #
#    type in bit: n = 2^bit                               #
#      first step:  n multiplications of 15 digits        #
#      middle step: n=n/2, digits=2*digits                #
#      last step :  1 multiplication of 15n digits        #
#    output file: mul_py.txt                              #
#---------------------------------------------------------#
#  copy right : Ushiro Yasunori (ISCPC)                   #
#    date : 2020/02/07                                    #
#=========================================================#
inport math,time

dec = 18
cst = 1
for k in range(dec):
   cst = cst * 10                         # cst=10^dec

print("typein bit(<=26), n=2^bit")
bit = int(input(">>"))                    # input bit
if bit > 26:
   bit = 26
n = 1 << bit                              # n=2^bit
a = [0]*n
print("Multiplication test start")

for k in range(n):
   a[k] = k + cst

def mul(a, n):                            # mul function
   for k in range(n):
      a[k] = a[k]*a[k+n]
   return a

fo = open("mul_py.txt", "w")              # open output file
n = n >> 1                                # n=n/2
dec = 18*2                                # 18*2 decimal

while n > 0:
   t1 = time.time()
   a = mul(a, n)                          # a[k]=a[k}*a[k+n}
   t2 = time.time()
   out1 ="out(keta,kazu):"+format(dec)+" * "+format(n) 
   out2 = ", time= "+"{:.2f}".format(t2-t1)+" (s)"
   print(out1+out2)
   fo.write(out1+out2+"\n")
   n = n >> 1                              # n = n/2
   dec = dec * 2