Add Check For Any Overlaps In List Of Ranges as a Ruby til

ruby/check-for-any-overlaps-in-list-of-ranges.md

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+# Check For Any Overlaps In List Of Ranges
+
+If you have a list of things, such as meetings, you may want to be able to tell
+if there are any conflicts. You could determine that by finding any overlaps in
+their timeslots.
+
+Ranges are a good way to represent any span of data, including a timeslot.
+
+To do this in Ruby, we'll need two pieces. First, a way to determine if two
+`Range` objects are overlapping. Second, an iterative utility for comparing
+each range to every other range.
+
+Here is an `overlaps?` method that uses `Range#begin` and `Range#end`.
+
+```ruby
+def overlaps?(range1, range2)
+  range1.begin <= range2.end && range2.begin <= range1.end
+end
+```
+
+And here is an `any_overlaps?` method to find any overlaps over a list of
+ranges.
+
+```ruby
+def any_overlaps?(ranges)
+  ranges.each_with_index do |range1, i|
+    ranges.each_with_index do |range2, j|
+      return true if i != j && overlaps?(range1, range2)
+    end
+  end
+
+  false
+end
+
+puts any_overlaps?([(1..2), (3..4)]) #=> false
+puts any_overlaps?([(1..2), (2..4)]) #=> true
+puts any_overlaps?([(3..4), (1..5)]) #=> true
+```
+
+This second method isn't optimized, but it will work just fine for small lists
+of ranges.
+
+[source](https://stackoverflow.com/questions/39934266/check-if-two-ranges-overlap-in-ruby)