Project Euler: Problem 8

https://projecteuler.net/problem=8

The four adjacent digits in the 1000-digit number that have the greatest product are 9 × 9 × 8 × 9 = 5832.

(see the number below)

Find the thirteen adjacent digits in the 1000-digit number that have the greatest product. What is the value of this product?

Use NumPy for this computation


In [3]:
import numpy as np

In [4]:
d1000 = "7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450"

In [5]:
t=[]
p=0
n=np.zeros(1000) #makes array of 1000 zeros
for i in range(len(d1000)): 
    n[i]=int(d1000[i]) #loops through list of numbers and makes them integers
for i in range(len(n)-12): #loops through the 13 adjacent numbers and appends the products to list t
    t.append(np.prod(np.array(n[i:i+13])))
    if t[i]>p: #replaces value of p if the previous value is larger
        p=t[i]
print(p)


23514624000.0

In [1]:
assert True # leave this for grading