contains duplicate solution

Author: radiantchoi

contains-duplicate/radiantchoi.swift

@@ -0,0 +1,15 @@
+class Solution {
+    func containsDuplicate(_ nums: [Int]) -> Bool {
+        var occurences = [Int: Bool]()
+
+        for num in nums {
+            if let occurs = occurences[num] {
+                return occurs
+            } else {
+                occurences[num] = true
+            }
+        } 
+
+        return false
+    }
+}