kt: add «2551. Put Marbles in Bags»

URL:	https://leetcode.com/problems/put-marbles-in-bags/
Signed-off-by: Matej Focko <me@mfocko.xyz>

kt/put-marbles-in-bags.kt

@@ -0,0 +1,18 @@
+class Solution {
+    fun putMarbles(
+        weights: IntArray,
+        k: Int,
+    ): Long =
+        weights
+            .zip(weights.drop(1))
+            .map { (w1, w2) -> (w1 + w2).toLong() }
+            .sorted()
+            .let { pairs ->
+                (0..k - 2)
+                    .map { i ->
+                        weights.size - 2 - i to i
+                    }.sumOf { (i, j) ->
+                        pairs[i] - pairs[j]
+                    }
+            }
+}