Create 0669-trim-a-binary-search-tree.kt

Author: a93a

Diff for: kotlin/0669-trim-a-binary-search-tree.kt

@@ -0,0 +1,23 @@
+/**
+ * Example:
+ * var ti = TreeNode(5)
+ * var v = ti.`val`
+ * Definition for a binary tree node.
+ * class TreeNode(var `val`: Int) {
+ *     var left: TreeNode? = null
+ *     var right: TreeNode? = null
+ * }
+ */
+class Solution {
+    fun trimBST(root: TreeNode?, low: Int, high: Int): TreeNode? {
+        if(root == null)
+            return null
+        if(root.`val` < low)
+            return trimBST(root.right, low, high)
+        else if(root.`val` > high)
+            return trimBST(root.left, low, high)
+        root.left = trimBST(root.left, low, high)
+        root.right = trimBST(root.right, low, high)
+        return root
+    }
+}