51c55cc459
Simple problem of abs values of primes. . . Working on problem 36 Signed-off-by: Julien Lengrand-Lambert <julien@lengrand.fr>
#My solutions to Project Euler 's website
Project Euler is a website containing lots of problems aiming at being solved. I play around with them in order to sharpen my algorithm skills.
This is always challenging to solve problems on paper and fantastic to come up with an algorithmic solution. I use Python for its simplicity. Simple Python code is very similar to paper solution, and fast to implement.
Each script runs by itself and contains one of several functions that directly solve the function. Thus, running a script should give you the answer directly.
The script are named as e_problemnumber_inc. The higher the inc, the finer my solution.
Here is a list of all already solved problems, with a one line explanation. Should be used in order to help future reuse of code :)
1 - Add all the natural numbers below one thousand that are multiples of 3 or 5. 2 - By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms. 3 - Find the largest prime factor of a composite number. 4 - Find the largest palindrome made from the product of two 3-digit numbers. 5 - What is the smallest number divisible by each of the numbers 1 to 20? 6 - What is the difference between the sum of the squares and the square of the sums? 7 - Find the 10001st prime. 8 - Discover the largest product of five consecutive digits in the 1000-digit number. 9 - Find the only Pythagorean triplet, {a, b, c}, for which a + b + c = 1000. (a^2 + b^2 = c^2) 10 - Calculate the sum of all the primes below two million. 11 - What is the greatest product of four adjacent numbers on the same straight line in the 20 by 20 grid? 12 - What is the value of the first triangle number to have over five hundred divisors? 13 - Find the first ten digits of the sum of one-hundred 50-digit numbers. 14 - Find the longest sequence using a starting number under one million. 15 - Starting in the top left corner in a 20 by 20 grid, how many routes are there to the bottom right corner? 16 - What is the sum of the digits of the number 2^1000? 17 - How many letters would be needed to write all the numbers in words from 1 to 1000? 18 - Find the maximum sum travelling from the top of the triangle to the base. 19 - How many Sundays fell on the first of the month during the twentieth century? 20 - Find the sum of digits in 100! 21 - Evaluate the sum of all amicable pairs under 10000. (d(a) = b, d(b) = a) 22 - What is the total of all the name scores in the file of first names? 23 - Find the sum of all the positive integers which cannot be written as the sum of two abundant numbers. 24 - What is the millionth lexicographic permutation of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9? 25 - What is the first term in the Fibonacci sequence to contain 1000 digits? 27 - Find a quadratic formula that produces the maximum number of primes for consecutive values of n. 48 - Find the last ten digits of 1^1 + 2^2 + ... + 1000^1000. 67 - Using an efficient algorithm find the maximal sum in the triangle?
**In progress: **
26 - Find the value of d < 1000 for which 1/d contains the longest recurring cycle. 36 - Find the sum of all numbers less than one million, which are palindromic in base 10 and base 2.
WARNING : Spoil inside for those who want to solve problems by themselves :)
Contact
I would enjoy having feedback if you try to solve euler's problems too :). Feel free to mail me for any comment or request.
You can contact me at julien@lengrand.fr, or on my current website