kt: add «2924. Find Champion II»

URL:	https://leetcode.com/problems/find-champion-ii/
Signed-off-by: Matej Focko <me@mfocko.xyz>

kt/find-champion-ii.kt

@@ -0,0 +1,21 @@
+class Solution {
+    fun findChampion(
+        n: Int,
+        edges: Array<IntArray>,
+    ): Int {
+        val degrees = IntArray(n)
+        for (edge in edges) {
+            degrees[edge[1]] += 1
+        }
+
+        val candidates =
+            degrees.withIndex().filter {
+                it.value == 0
+            }.take(2)
+
+        return when {
+            candidates.size == 1 -> candidates.first().index
+            else -> -1
+        }
+    }
+}