kt: add «1325. Delete Leaves With a Given Value»

Signed-off-by: Matej Focko <me@mfocko.xyz>

kt/delete-leaves-with-a-given-value.kt

@@ -0,0 +1,28 @@
+class TreeNode(var `val`: Int) {
+    var left: TreeNode? = null
+    var right: TreeNode? = null
+}
+
+class Solution {
+    fun isLeaf(node: TreeNode?): Boolean {
+        return node != null && node.left == null && node.right == null
+    }
+
+    fun removeLeafNodes(
+        root: TreeNode?,
+        target: Int,
+    ): TreeNode? {
+        if (root == null) {
+            return null
+        }
+
+        root.left = removeLeafNodes(root.left, target)
+        root.right = removeLeafNodes(root.right, target)
+
+        if (isLeaf(root) && root.`val` == target) {
+            return null
+        }
+
+        return root
+    }
+}