shinokada

# 1.
a = [1, 2, 3]
b = [1, 4, 3]

a.zip(b).map { |x, y| x == y } # [true, false, true]A

# 2.
a.zip(b).collect {|x,y| x==y }
# => [true, false, true]

shinokada

# find number of item which has at least 3 numbers are the same

arr1 = [1, 2, 3, 4]

arr2 = [[2, 2, 2, 4],[1, 4, 3, 4],[1, 2, 1, 4],[1, 2, 3, 1],[2, 1, 3, 4]]
n = 0
arr2.map{|e| e.zip(arr1).collect{| x, y| x==y}}.each do |e| 
  if e.count(true) >=3
    n += 1
  end

shinokada

  def readfile1(file_name)
    # read a file and returns string "17 10 16 3 7 "
    file = File.open(file_name)
    contents = file.read.gsub(/\r\n/, ' ')
  end

  def readfile2(file_nam)
    # same as above
    File.readlines(file_name).map(&:chomp).join(' ')
  end

shinokada

# Ruby: How to find and return a duplicate value in array?

ary = ["A", "B", "C", "B", "A"]

ary.group_by { |e| e }.select { |k, v| v.size > 1 }.map(&:first) # => ["A", "B"]

ary.sort.chunk { |e| e }.select { |e, count| count.size > 1 }.map(&:first)

ary.select { |e| ary.count(e) > 1 }.uniq # => ["A", "B"]

shinokada

# file content
#
# 4
# bar
# abracadabra
# bear
# bar
# baraxbara

shinokada

# file content
#
# 17
# 10
# 16
# 3
# 7

File.readlines(file_name).map(&:chomp).map(&:to_i)
# read number to array [17, 10, 16, 3, 7]

shinokada

$: << File.join(File.dirname(__FILE__), '..', 'lib')

require 'pry' if ENV['APP_ENV'] == 'debug' # add `binding.pry` wherever you need to debug
require 'fish'

def read_file_to_arr(file_name)
  # ['17, 10, 16 3, 7']
  # ["4", "bar", "abracadabra", "bear", "bar", "baraxbara"] 
  File.readlines(file_name).map(&:chomp)
end

shinokada

# Assign array values to different variables
a = [99, 97, 89, 99, 97]
v1, v2, *v3 = a.join(',').split(',')
# => ["99", "97", "89", "99", "97"]
v1
# => "99"
v2
# => "97"
v3
# => ["89", "99", "97"]

shinokada

def  insertionsort(num)
  for j in 1..(num.length - 1) do
    key = num[j]
    i = j - 1
    while i >= 0 and num[i] > key
      num[i+1] = num[i]
      i = i - 1
    end
    num[i+1] = key
  end

shinokada

# return max hash key-value pair
def largest_hash_key(hash)
  hash.max_by{|k,v| v}
end

hash = {"ZZ" => 0, "CA"=>2, "MI"=>1, "NY"=>1}
p largest_hash_key(hash) # return  ["CA", 2]

# return largest hash key pair
p hash.max