Create 1359-count-all-valid-pickup-and-delivery-options.kt

Author: a93a

kotlin/1359-count-all-valid-pickup-and-delivery-options.kt

@@ -0,0 +1,15 @@
+class Solution {
+    fun countOrders(n: Int): Int {
+        var slots = 2 * n
+        var res = 1L
+        val mod = 1_000_000_007
+
+        while (slots > 0) {
+            val choices = (slots * (slots - 1) % mod) / 2
+            res = (res * choices) % mod
+            slots -= 2
+        }
+
+        return res.toInt()
+    }
+}