ProjectEuler Python One liners

projeuler_oneliners.py

# Problem 1
"""Find the sum of all the multiples of 3 or 5 below 1000."""

sum( [ num for num in range(3,1000) if num % 3 == 0 or num % 5 == 0 ] )


# Problem 4
"""
A palindromic number reads the same both ways. The largest palindrome 
made from the product of two 2-digit numbers is 9009 = 91  99.
Find the largest palindrome made from the product of two 3-digit numbers.
"""
print max(filter( lambda x : str(x) == str(x)[::-1], 
          reduce(list.__add__, 
          [ [i * r for i in range(100,1000)]  for r in range(100,1000) ] )))

# Update : Figured out that we can create a 1-D list using nested loops like this:

print max(filter( lambda x : str(x) == str(x)[::-1], 
          [ i * r for i in range(100,1000)  for r in range(100,1000) ] ))


# Problem 6
"""
The sum of the squares of the first ten natural numbers is,

1^2 + 2^2 + ... + 10^2 = 385
The square of the sum of the first ten natural numbers is,

(1 + 2 + ... + 10)^2 = 552 = 3025
Hence the difference between the sum of the squares of the first 
ten natural numbers and the square of the sum is 3025  385 = 2640.

Find the difference between the sum of the squares of the 
first one hundred natural numbers and the square of the sum.
"""

( sum ( range(1,101) ) ** 2) -  sum([ x*x for x in range(1,101)] )


# Problem 8

"""
Find the greatest product of five consecutive 
digits in the 1000-digit number.
"""

num = ''.join("""
73167176531330624919225119674426574742355349194934
96983520312774506326239578318016984801869478851843
85861560789112949495459501737958331952853208805511
12540698747158523863050715693290963295227443043557
66896648950445244523161731856403098711121722383113
62229893423380308135336276614282806444486645238749
30358907296290491560440772390713810515859307960866
70172427121883998797908792274921901699720888093776
65727333001053367881220235421809751254540594752243
52584907711670556013604839586446706324415722155397
53697817977846174064955149290862569321978468622482
83972241375657056057490261407972968652414535100474
82166370484403199890008895243450658541227588666881
16427171479924442928230863465674813919123162824586
17866458359124566529476545682848912883142607690042
24219022671055626321111109370544217506941658960408
07198403850962455444362981230987879927244284909188
84580156166097919133875499200524063689912560717606
05886116467109405077541002256983155200055935729725
71636269561882670428252483600823257530420752963450
""".split('\n') )  # weird way to read the data.

print max( [ reduce( lambda x, y: int(x) * int (y), 
                     [c for c in (num[i : i + 5])] ) for i in range( len(num) - 5 ) ] )



# Problem 20

"""
n! means n  (n  1)  ...  3  2  1
For example, 10! = 10  9  ...  3  2  1 = 3628800,
and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.

Find the sum of the digits in the number 100!
"""


sum( map ( int , [c for c in str( reduce( lambda x, y: x * y, range(1, 101) ) ) ]  ))