added TrimBST

Author: saihariG

Trees/TrimBinarySearchTree.java

@@ -0,0 +1,25 @@
+package Trees;
+
+public class TrimBinarySearchTree {
+    static class TreeNode {
+        int val;
+        TreeNode left,right;
+    }
+
+    private TreeNode trimBST(TreeNode root, int low,int high) {
+        if(root == null) return null;
+
+        if(root.val >= low && root.val <= high) {
+            root.left = trimBST(root.left,low,high);
+            root.right = trimBST(root.right,low,high);
+        }
+        else if(root.val < low) {
+            root = trimBST(root.right,low,high);
+        }
+        else if(root.val > high) {
+            root = trimBST(root.left,low,high);
+        }
+
+        return root;
+    }
+}