Solutions for 1, 2, 4

numUnique.rb

@@ -0,0 +1,30 @@
+# list = [5, 7, 7, 7, 8, 22, 22, 23, 31, 35, 35, 40, 40, 40, 41]
+# numUnique(list) = 9
+
+# list = [1, 2, 11, 17, 19, 20, 23, 24, 25, 26, 31, 34, 37, 40, 41]
+# numUnique(list) = 15
+
+# list = []
+# numUnique = 0
+
+def numUnique(arr)
+  # empty hash
+  my_h = {}
+  # go through the Array
+  arr.each do |number|
+  # first number: the key is the value of the first number, value is 1
+  # second number: does it equal the first key?
+  # if so, first key's value increments one
+  # if not, the new key is the value of the second number, value is 1
+  # third number: does it equal the second key?
+  # if so, value of second key increments one
+  # if not, the new key is the value of the third number, value is 1
+  # etc
+  # What is the size of the hash?
+    if my_h[num]
+      my_h[num] += 1
+    else
+      my_h[num] = 1
+    end
+  return my_h.length
+end

numUnique2.rb

@@ -0,0 +1,15 @@
+def numUnique2(arr)
+  place_marker = 0
+  counter = 0
+
+  arr.each do |number|
+    if arr[place_marker] != arr [place_marker-1]
+      counter += 1
+      place_marker += 1
+    else
+      place_marker += 1
+    end
+  end
+
+  return counter
+end

print_list.rb

@@ -0,0 +1,30 @@
+# list = [3, 19, 27, 4, 98, 304, -9, 72]
+# print_list(list) = [3, 19, 27, 4, 98, 304, -9, 72]
+#
+# Questions I had:
+# Is the return value a string, or another array?
+# If it's a string, is string interpolation ok?
+
+# Solution for string output
+def print_list(arr)
+  my_s = "["
+  # beginning of the string has the opening bracket
+  arr[0...arr.length-1].each { |x| my_s += "#{x}, " }
+  # add on each value in the array with a comma and space, except for the last value
+  my_s += "#{arr[-1]}"
+  # add on the last value, which doesn't have a comma and space
+  my_s += "]"
+  # add on the closing bracket
+  return my_s
+  # the entire string
+end
+
+# Solution for array output (not sure if this is allowed, though)
+def print_list(arr)
+  string = []
+  # new empty array
+  arr[0...arr.length].each { |x| string << x }
+  # shovel each value into new empty array
+  return string
+  # prints the new array (arrays are printed as comma-separated lists enclosed in brackets)
+end

stretch.rb

@@ -0,0 +1,22 @@
+# list = [18, 7, 4, 24, 11]
+# stretch(list) = [9, 9, 4, 3, 2, 2, 12, 12, 6, 5]
+
+def stretch(arr)
+  # new empty array
+  new_arr = []
+  # go through each element
+  arr.each do |number|
+    # if even, divide by two
+    if number % 2 == 0
+      new_arr << (number / 2)
+      new_arr << (number / 2) # this isn't DRY, I think
+    # if odd, subtract one, divide by two. Add one to the first half
+    else
+      new_arr << (((number - 1) / 2) + 1)
+      new_arr << ((number - 1) / 2) # DRY-ness issue here, maybe
+    # store both halves
+    end
+  end
+  # return new array
+  return new_arr
+end