merge sort

mergesort.rb

# Sort the array from lowest to highest
def sort(arr)
# if the size of array is less than or 1 output that item
  arrlen = arr.length
  if arrlen <= 1
    return arr
  else
    mid = arrlen/2 #finding the middle of the array
    leftarr = arr[0..mid-1]#splitting it into the first half of the array
    rightarr = arr[mid ..arrlen]#splitting it to second half of array up to the last index of the array
    merge(leftarr, rightarr) 
  end
end
#we had to create a second method here to merge the arrays after we go through the loop
def merge(leftarr, rightarr)
  if leftarr.empty?
    return rightarr
  elsif rightarr.empty?
    return leftarr
  elsif leftarr.first < rightarr.first
    leftarr[0..1-1] + merge(leftarr[1..leftarr.length], rightarr)
  else 
     rightarr[0..1-1] + merge(leftarr, rightarr[1..rightarr.length])
  end
end

# Find the maximum 
def maximum(arr)
  sort(arr).last

end

def minimum(arr)
  sort(arr).first
end
 
# expect it to return 42 below
result = maximum([2, 42, 22, 02])
puts "max of 2, 42, 22, 02 is: #{result}"

# expect it to return 2 below
result = minimum([2, 42, 22, 02])
puts "min of 2, 42, 22, 02 is: #{result}"

 
# expect it to return nil when empty array is passed in
result = maximum([])
puts "max on empty set is: #{result.inspect}"
result = minimum([])
puts "min on empty set is: #{result.inspect}"
 
result = maximum([-23, 0, -3])
puts "max of -23, 0, -3 is: #{result}"
 
result = maximum([6])
puts "max of just 6 is: #{result}"