From 725906c2e8bb457696d08eb7ec14b374cd6dbd5d Mon Sep 17 00:00:00 2001
From: Steven Proctor <steven.proctor@gmail.com>
Date: Sat, 10 Jan 2026 17:19:28 -0600
Subject: [PATCH] create ordered sequence of the given ranges' start and end
 values

---
 src/challenge/discrete_value_range.clj       | 26 +++++++++++++++++++-
 test/challenge/discrete_value_range_test.clj | 20 +++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/src/challenge/discrete_value_range.clj b/src/challenge/discrete_value_range.clj
index 8193f30..a8dc9c0 100644
--- a/src/challenge/discrete_value_range.clj
+++ b/src/challenge/discrete_value_range.clj
@@ -27,4 +27,28 @@
   (value-before [this])
   (value-after [this])
   (start [this])
-  (end [this]))
+  (end [this])
+  (range-type [this]))
+
+(defn- ordered-range-values
+  "Builds an ordered list or 'fenceposts' for the start and end
+  of all given ranges, to prepare to produces a consolidated
+  set of ranges, by doing open/close count matching.
+
+  By building this list, it will allow us to push a `start`
+  onto a stack, and `pop` when we encounter an `end.`
+
+  If we pop, and get an empty stack, we have found the item
+  that represents the end value that matches the start value
+  that we just popped off the stack, and are able to ignore
+  any intermediate matching starts/stops."
+  [ranges]
+  (->> ranges
+       (mapcat (fn [range]
+                 [{:value (start range)
+                   :boundary-type :start
+                   :type (range-type range)}
+                  {:value (end range)
+                   :boundary-type :end
+                   :type (range-type range)}]))
+       (sort-by (juxt :value (comp {:start 0 :end 1} :boundary-type)))))
diff --git a/test/challenge/discrete_value_range_test.clj b/test/challenge/discrete_value_range_test.clj
index af1da3b..df51735 100644
--- a/test/challenge/discrete_value_range_test.clj
+++ b/test/challenge/discrete_value_range_test.clj
@@ -17,6 +17,8 @@
     start)
   (end [_this]
     end)
+  (range-type [_this]
+    :int-range-inclusive)
 
   Object
   (toString [_this]
@@ -51,3 +53,21 @@
     (is (= 1 (range/start (int-range-inclusive 1 8)))))
   (testing "end"
     (is (= 8 (range/end (int-range-inclusive 1 8))))))
+
+(deftest ordered-range-values
+  (testing "ordered range values are sorted by value and then the range's start boundary before any end boundary"
+    (is (= [{:value 4 :boundary-type :start :type :int-range-inclusive}
+            {:value 5 :boundary-type :start :type :int-range-inclusive}
+            {:value 5 :boundary-type :start :type :int-range-inclusive}
+            {:value 5 :boundary-type :end :type :int-range-inclusive}
+            {:value 5 :boundary-type :end :type :int-range-inclusive}
+            {:value 8 :boundary-type :end :type :int-range-inclusive}]
+           (#'range/ordered-range-values [(int-range-inclusive 4 5)
+                                          (int-range-inclusive 5 8)
+                                          (int-range-inclusive 5 5)])))
+    (is (= [{:value 5 :boundary-type :start :type :int-range-inclusive}
+            {:value 5 :boundary-type :start :type :int-range-inclusive}
+            {:value 5 :boundary-type :end :type :int-range-inclusive}
+            {:value 5 :boundary-type :end :type :int-range-inclusive}]
+           (#'range/ordered-range-values [(int-range-inclusive 5 5)
+                                          (int-range-inclusive 5 5)])))))