From fade1fc2188712c42f3bb33ccdcd0d0243e8841b Mon Sep 17 00:00:00 2001
From: joachimschmidt557 <joachim.schmidt557@outlook.com>
Date: Fri, 13 Sep 2019 19:06:46 +0200
Subject: [PATCH] WIP bst

---
 bst.rkt | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/bst.rkt b/bst.rkt
index b349c8c..1fa4ce0 100644
--- a/bst.rkt
+++ b/bst.rkt
@@ -20,13 +20,12 @@
     [(empty? lst) empty]
     [else (insert (bst-from-list (rest lst)) (first lst))]))
 
-(define (rotate-left node)
+(define (rotate-right node)
   (if (empty? node) empty
       (let ([x node] [l (node-left node)] [r (node-right node)])
         (let ([a (if (empty? l) empty (node-left l))]
               [b (if (empty? l) empty (node-right l))]
-              [c (if (empty? r) empty (node-left r))]
-              [d (if (empty? r) empty (node-right r))])
+              [c (if (empty? r) empty (node-left r))])
           (make-node (node-value l) a (make-node (node-value x) b r))))))
 
 (define (height node)
@@ -37,10 +36,22 @@
 (define (avlcheck node)
   (cond
     [(empty? node) 0]
-    [(= (height (node-left node)) -1) -1]
-    [(= (height (node-right node)) -1) -1]
-    [(< 1 (abs (- (height (node-left node)) (height (node-right node))))) -1]
-    [else (+ 1 (max (height (node-left node)) (height (node-right node))))]))
+    [(= (avlcheck (node-left node)) -1) -1]
+    [(= (avlcheck (node-right node)) -1) -1]
+    [(< 1 (abs (- (avlcheck (node-left node)) (avlcheck (node-right node))))) -1]
+    [else (+ 1 (max (avlcheck (node-left node)) (avlcheck (node-right node))))]))
+
+(define (min-subtree node)
+  (cond
+    [(empty? node) empty]
+    [(empty? (node-left node)) node]
+    [else (min-subtree (node-left node))]))
+
+(define (max-subtree node)
+  (cond
+    [(empty? node) empty]
+    [(empty? (node-right node)) node]
+    [else (max-subtree (node-right node))]))
 
 (define (delete node)
   (cond