[Array] Add a solution to Heaters

Array/Heaters.swift

@@ -0,0 +1,23 @@
+/**
+ * Question Link: https://leetcode.com/problems/heaters/
+ * Primary idea: Two pointers, get the closest heater for the house, and update radius
+ * Time Complexity: O(nlogn), Space Complexity: O(1)
+ *
+ */
+
+class Heaters {
+    func findRadius(_ houses: [Int], _ heaters: [Int]) -> Int {
+        var i = 0, radius = 0
+        let houses = houses.sorted(), heaters = heaters.sorted()
+
+        for house in houses {
+            while i < heaters.count - 1 && 2 * house >= heaters[i] + heaters[i + 1]  {
+                i += 1
+            }
+
+            radius = max(radius, abs(house - heaters[i]))
+        }
+
+        return radius
+    }
+}