NoMan2000 · March 10, 2019 22:40 · Mar 10, 2019
diff --git a/missing_numbers.rb b/missing_numbers.rb
@@ -0,0 +1,86 @@
+require "test/unit"
+
+NOT_A_NUMBER = 1
+ALL_GOOD = 0
+
+def update_previous_value_if_one_ahead(i, prev)
+  if prev == nil
+    prev = i.to_i
+  else
+    check_value = prev.to_i + 1
+    if check_value == i
+      prev = i.to_i
+    end
+  end
+  prev.to_i
+end
+
+def find_missing_number(sequence)
+  arr = sequence.split(' ')
+  unless arr.length
+    return ALL_GOOD
+  end
+  prev = nil
+
+
+  arr.each do |i|
+    # Check if not a number
+    if i =~ /\D/
+      return NOT_A_NUMBER
+    end
+    i = i.to_i
+    # Wouldn't normally recommend this approach.
+    if prev == nil and i == 2
+      return 1
+    end
+    prev = update_previous_value_if_one_ahead(i, prev)
+
+    if i != prev
+          return prev + 1
+    end
+  end
+  ALL_GOOD
+end
+
+class BLUR_TEST < Test::Unit::TestCase
+
+  def test_will_return_one_if_not_a_number
+    assert_equal(NOT_A_NUMBER, find_missing_number('a'))
+  end
+
+  def test_will_return_missing_number
+    assert_equal(
+        4,
+        find_missing_number("1 2 3 5"),
+        "It must work for missing middle terms")
+  end
+
+  def test_will_return_missing_number_two
+    assert_equal(
+        2,
+        find_missing_number("1 3")
+    )
+  end
+
+  def test_will_return_0_for_empty_set
+    assert_equal(
+        0,
+        find_missing_number("")
+    )
+  end
+
+  def test_will_return_missing_number_again
+    assert_equal(
+        1,
+        find_missing_number("2 3 4 5")
+    )
+  end
+  def test_will_return_1_on_invalid_sequence
+    assert_equal(
+        1,
+        find_missing_number("2 1 4 3 a")
+    )
+  end
+
+end
+