kt: add «1352. Product of the Last K Numbers»

URL:	https://leetcode.com/problems/product-of-the-last-k-numbers/
Signed-off-by: Matej Focko <me@mfocko.xyz>

kt/product-of-the-last-k-numbers.kt

@@ -0,0 +1,22 @@
+class ProductOfNumbers() {
+    private val prefix: MutableList<Int> = mutableListOf(1)
+    private val size: Int
+        get() = prefix.size - 1
+
+    fun add(num: Int) =
+        when (num) {
+            0 -> {
+                prefix.clear()
+                prefix.add(1)
+            }
+            else -> {
+                prefix.add(prefix[size] * num)
+            }
+        }
+
+    fun getProduct(k: Int): Int =
+        when {
+            k > size -> 0
+            else -> prefix[size] / prefix[size - k]
+        }
+}