# Functional Programming

## Project Euler – Problem 9 Solution

Problem A Pythagorean triplet is a set of three natural numbers, a < b < c, for which, a2 + b2 = c2 For example, 32 + 42 = 9 + 16 = 25 = 52. There exists exactly one Pythagorean triplet for which a + b + c = 1000. Find the product abc. …

## Project Euler – Problem 8 Solution

Problem Find the greatest product of five consecutive digits in the 1000-digit number. 73167176531330624919225119674426574742355349194934 96983520312774506326239578318016984801869478851843 85861560789112949495459501737958331952853208805511 12540698747158523863050715693290963295227443043557 66896648950445244523161731856403098711121722383113 62229893423380308135336276614282806444486645238749 30358907296290491560440772390713810515859307960866 70172427121883998797908792274921901699720888093776 65727333001053367881220235421809751254540594752243 52584907711670556013604839586446706324415722155397 53697817977846174064955149290862569321978468622482 83972241375657056057490261407972968652414535100474 82166370484403199890008895243450658541227588666881 16427171479924442928230863465674813919123162824586 17866458359124566529476545682848912883142607690042 24219022671055626321111109370544217506941658960408 07198403850962455444362981230987879927244284909188 84580156166097919133875499200524063689912560717606 05886116467109405077541002256983155200055935729725 71636269561882670428252483600823257530420752963450 Solution To get the 1000 digits into the program, I copied and pasted the digits into a text file and saved it …

## Project Euler – Problem 7 Solution

Problem By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13. What is the 10001st prime number? Solution Here I borrowed the findFactors and isPrime functions I first used in the problem 3 solution, except this time they don’t have to be …

## Project Euler – Problem 6 Solution

Problem The sum of the squares of the first ten natural numbers is, 12 + 22 + … + 102 = 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 …

## Project Euler – Problem 5 Solution

Problem 2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder. What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20? Solution Again, I build two functions to handle the logic of checking whether a …

## Project Euler – Problem 4 Solution

Problem A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 x 99. Find the largest palindrome made from the product of two 3-digit numbers. Solution In my solution above, I first built a function to check whether a given number is …

## Project Euler – Problem 3 Solution

Problem The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number 600851475143 ? Solution As this solution requires a bit more work, I created two helper functions findFactorsOf and isPrime, and as you’ve probably noticed, I had explicitly declare that the value n should be …

## Project Euler – Problem 2 Solution

Problem Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be: 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, … Find the sum of all the even-valued terms in the sequence which do not exceed four …

## Project Euler – Problem 1 Solution

Introduction Having spent a bit of time learning the basics of F# I decided to try my hands on actually writing some code and get a better feel of the language and get more used to writing function code in general. And for that purpose, Project Euler provides a great source for small, isolated problems …

## Functional programming with Linq – Enumerable.SequenceEqual

Yet another useful method on the Enumerable class, the SequenceEqual method does exactly what it says on the tin and tells you whether or not two sequences are of equal length and their corresponding elements are equal according to either the default or supplied equality comparer: As you know, for reference types the default equality …