jkaihsu’s gists

jkaihsu / arithmetic.rb

Created March 7, 2013 08:13

Define four methods which correspond to the four basic arithmetic operations: add, subtract, multiply, divide.They should accept either integers or floating point numbers as input. divide should perform floating point division.

	def add(x,y)
	x + y
	end

	def subtract(x,y)
	x - y
	end

	def multiply(x,y)
	x * y

jkaihsu / count_bwtn.rb

Created March 7, 2013 08:15

Write a method count_between which takes three arguments as input: An Array of integers An integer lower bound An integer upper bound count_between should return the number of integers in the Array between the two bounds, including the bounds It should return 0 if the Array is empty.

	def count_between(array, lower_bound, upper_bound)
	array.count{\|x\| x >= lower_bound && x <= upper_bound}
	end

jkaihsu / mode.rb

Created March 7, 2013 08:16

Write a method mode which takes an Array of numbers as its input and returns an Array of the most frequent values. If there's only one most-frequent value, it returns a single-element Array. For example, mode([1,2,3,3]) # => [3] mode([4.5, 0, 0]) # => [0] mode([1.5, -1, 1, 1.5]) # => [1.5] mode([1,1,2,2]) # => [1,2] mode([1,2,3]) # => [1,2,3], b…

	def mode(array)
	mode = array.inject(Hash.new(0)) { \|h,v\| h[v] = h[v] + 1; h}
	mode.select{ \|h,v\| v == mode.values.max }.keys
	end

jkaihsu / longest_string.rb

Created March 7, 2013 08:17

Write a method longest_string which takes as its input an Array of Strings and returns the longest String in the Array. For example: # 'zzzzzzz' is 7 characters long longest_string(['cat', 'zzzzzzz', 'apples']) # => "zzzzzzz" If the input Array is empty longest_string should return nil.

	def longest_string(array)

	if array.empty?
	nil
	else
	long_string = array.group_by(&:size).max.last
	long_string[0]
	end
	end

jkaihsu / triangle.rb

Created March 7, 2013 08:19

Write a method print_triangle which takes at its input an integer representing the number of rows to print, and prints out a right triangle consisting of * characters, one line per row. For example, print_triangle(5) should print out:

	def print_triangle(rows)
	for j in 1..rows do
	for i in 1..j do
	print "" 1
	end
	puts
	end
	end

jkaihsu / reverse_words.rb

Created March 7, 2013 08:20

Write a method reverse_words which takes a sentence as a string and reverse each word in it.

	def reverse_words(str)
	words = str.split(' ')
	reverse_str = []

	words.length.times do \|i\|
	reverse_str[i] = words[i].reverse
	end


	return reverse_str.join(" ")

jkaihsu / commas1.rb

Created March 7, 2013 08:21

Write a method separate_comma which takes an integer as its input and returns a comma-separated integer as a string.

	def separate_comma(number)
	number.to_s.reverse.gsub(/(\d{3})(?=\d)/, '\\1,').reverse
	end

jkaihsu / fibonacci.rb

Created March 7, 2013 08:22

Check, if a number i is part of the Fibonacci sequence.

	def is_fibonacci?(i)

	sum = [0,1]
	x = 0
	y = 0
	while sum.max <= i
	sum.length.times do \|a\|
	x = sum[a] + sum[a-1]

	end

jkaihsu / pad.rb

Created March 7, 2013 08:23

Implement Array#pad and Array#pad!. Each method accepts a minimum size (non-negative integer) and an optional pad value as arguments. If the array's length is less than the minimum size, Array#pad should return a new array padded with the pad value up to the minimum size. For example, ruby [1,2,3].pad(5) should return [1,2,3,nil,nil] And ruby [1…

	class Array
	def pad!(min_size, value = nil)
	x = min_size - self.count
	x.times {self << value}
	self
	end

	def pad(min_size, value = nil)
	self.clone.pad!(min_size, value)
	end

jkaihsu / sudoku_refactoring.rb

Created March 19, 2013 15:06

Not done yet.

	class Sudoku

	def initialize(string)
	string_of_array = string.split("")
	@board = Array.new(9) {string_of_array.shift(9)}
	end


	def solve!
	first_empty = find_empty_cell

J-kai Hsu jkaihsu