feat(kt/problems): add contains duplicate

Author: barbarosaffan

kt/src/main/kotlin/problems/ContainsDuplicate.kt

@@ -0,0 +1,22 @@
+package problems
+
+fun containsDuplicate(nums: IntArray): Boolean {
+    val seenNumbers = HashSet<Int>()
+
+    for (num in nums) {
+        if (seenNumbers.contains(num)) {
+            return true
+        }
+        seenNumbers.add(num)
+    }
+
+    return false
+}
+
+fun main() {
+    println("Contains Duplicate")
+
+    val nums = intArrayOf(1, 1, 1, 3, 3, 4, 3, 2, 4, 2)
+
+    println(containsDuplicate(nums))
+}