Created
January 13, 2016 15:55
-
-
Save stoffie/70d195a14cd8eacb64df to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
# Find the longest string in a vector | |
# Count the number of upcased letter in a string | |
# Reverse an hash inside out, ie: | |
# {a: :b} becomes {b: :a} | |
# Find if an array has nested arrays | |
# Find how deep an array is, ie how many arrays are nested in it | |
# Parse an IPv4 Address | |
# Encode a string into morse-code (only for some letters) | |
# Implement the factorial function | |
def factorial(n) | |
(1 .. n).inject(:*) | |
end | |
# Find the first factorial number greater than m | |
def factorial_bigger_than(m) | |
(1 .. Float::INFINITY).lazy.map { |i| factorial(i) }.find { |j| j > m } | |
end | |
p factorial_bigger_than(1000) | |
# If we list all the natural numbers below 10 that are multiples of 3 we get 3, 6, 9. The sum of these multiples is 18. | |
def sum_of_multiplier(multiplier, max) | |
range = 1 .. max | |
range.select { |i| (i % multiplier) == 0 }.inject(:+) | |
end | |
# Find the sum of all the multiples of 3 below 1000. | |
p sum_of_multiplier(3, 1000) | |
# Multiples of 3 and 5 | |
# If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23. | |
def sum_of_multipliers(multipliers, max) | |
range = 1 .. max | |
range.select { |i| | |
multipliers.any? { |m| | |
(i % m) == 0 | |
} | |
}.inject(:+) | |
end | |
# Find the sum of all the multiples of 3 or 5 below 1000. | |
p sum_of_multipliers([3, 5], 1000) | |
# Implement the fibonacci sequence | |
# By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms. | |
# Determine if a number is prime | |
#Largest prime factor | |
#The prime factors of 13195 are 5, 7, 13 and 29. | |
#What is the largest prime factor of the number 600851475143 ? | |
#Palindrome number | |
# determine if a number is palindrome or not | |
#Largest palindrome product | |
#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. | |
# Sum square difference | |
# Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum. | |
# Special Pythagorean triplet | |
# 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. | |
#Power digit sum | |
#2^15 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26. | |
#What is the sum of the digits of the number 2^1000? |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment